- 1 Pregnancy – Parturition, Lactation, and Gestation Period
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Pregnancy – Parturition, Lactation, and Gestation Period
It is the time from conception to birth, in human beings it is approximately 9 months and 7-10 days.
The days of pregnancy are calculated from the first day of the last menstrual period, or 256-270 days from the time of ovulation. Various types of extra demands are observed on the mother’s body during the period of pregnancy. The physiological changes during pregnancy include-
- To accommodate the growing fetus there is a marked increase in the size of the uterus takes place.
- During the first 12-16 weeks of pregnancy, the corpus luteum enlarges. After some time it degenerates and the placenta takes over the function.
- In the cervix, the cervical gland increase in number, endocervix gets hypertrophied.
- Fallopian tubes are pushed upwards due to an increase in the size of the uterus. Hyperplasia of fallopian tubes occurs.
- During early pregnancy, under the influence of various hormones breast enlarges. Ductae and alveolar hyperplasia occur. Nipples also become longer and pigmented.
- During this period a woman gains a total of 10-12 kg of weight contributed by fetus, placenta and amniotic fluid, uterus and breast enlargement, fat deposition, Na+, and H2O retention (edema).
Different Stages of Development of Foetus:
|1 week||About 4-5 days after fertilization zygote first form morula and then blastula by division process. Blastula is then implanted into the endometrium layer of the uterus (6-9 days after fertilization).|
|2 weeks||Blastula is now converted into gastrula which contains three germ layers (ectoderm, mesoderm, and endoderm).|
|3 weeks||Stoppage of the female menstrual cycle indicates conception which means pregnancy occurred. The neural tube, brain, and spinal cord development occur in the fetus.|
|4 weeks||Heart, blood, and blood vessels start forming. Foetus is now 5 mm in length umbilical cord develop.|
|5 weeks||The limb bud originates from the development of the hands and legs. The brain becomes enlarged and the fetus is now 8 mm in length. The appearance of heart sound, which is detectable through ultrasound.|
|6 weeks||The appearance of ears and eyes.|
|7 weeks||Foetus is now 17 mm in length. All major internal organs develop. The face appears along with the oral cavity and tongue. Eyes have a dark color. Hand and legs arise.|
|10-12 weeks||Except for gonads, all organs develop. Fingers (hands and legs) become prominent. The fetus starts moving. Foetus is now approximately 56 mm in length. The pregnant condition is now evident.|
|20 weeks||In most circumstances, 24 weeks is the legal limit for abortion. Eyelids are open now.|
|24 weeks||If prematurely born it is a good time to have a chance of survival.|
|26 weeks||Baby moving out vigorously. The quantity of amniotic fluid is increased. Now baby responds to touch and loud noise.|
|28 weeks||Urinating and swallowing amniotic fluid.|
|30 weeks||Now fetus is 250 mm in length. A complete portion or image of the child is developed, and the head is lying down.|
|40 weeks (9 months ± 7 to 10 days)||The weight of a normal healthy baby is 2.5-3 kg. Labour pain occurs. Birth of the baby.|
The intimate connection established between the fetal membrane and the uterine wall of the mother is known as the placenta. The placenta is an organ that links the developing foetus to the mother to allow nutrient uptake, provide thermoregulation to the fetus, waste elimination and gas exchange via the mother’s blood supply, fight against internal infection, and produce hormones to support pregnancy.
Structure of Placenta
The placenta provides oxygen and nutrients to the growing foetus and removes waste products from the fetus’s blood. The placenta attaches to the wall of the uterus and the baby’s umbilical cord develops from the placenta. The umbilical cord is what actually connects the mother and the baby. Placentas are a defining characteristic of placental mammals but are also found in some non-mammals with varying levels of development.
The outer surface of the chorion in human develops a number of finger-like projections, known as chorionic villi, which grow into the tissue of the uterus. These villi penetrate the tissues of the uterine wall in which they are embedded, making up the organ known as the placenta. The developing embryo obtains nutrients and oxygen through the placenta and gets rid of carbon dioxide and metabolic wastes. The human placenta is called the chorionic placenta. It consists of the fetal part, the chorion, and a maternal part the decidua bases. The foetal part of the placenta grows to invade the uterine mucosa with its chorionic villi.
The degree of intimacy is so strong that the blood vessels of the chorion are bathed in the mother’s blood. This type of placenta which is based on the intimacy between the fetal and maternal parts of the placenta is called the haemochorial placenta. The placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo. On the basis of the distribution of villi in the chorion, the human placenta is called the metadiscoidal placenta.
The placenta begins to develop upon implantation of the blastocyst into the maternal endometrium. The outer layer of the blastocyst becomes the trophoblast, which forms the outer layer of the placenta. This outer layer is divided into two further layers: the underlying cytotrophoblast layer and the overlying syncytiotrophoblast layer which is a multinucleated continuous cell layer that covers the surface of the placenta. It forms as a result of differentiation and fusion of the underlying cytotrophoblast cells, a process that continues throughout the development of the placenta. This syncytiotrophoblast contributes to the barrier function of the placenta. The placenta grows throughout the pregnancy. The development of maternal blood supply to the placenta is completed by the end of the first trimester of pregnancy.
Functions of Placenta
The placenta performs the following functions:
The nutritive elements from the maternal blood pass into the foetus through the placenta. The perfusion of the intervillous spaces of the placenta with maternal blood allows the transfer of nutrients and oxygen from the mother to the foetus and the transfer of waste products and carbon dioxide back from the foetus to the maternal blood supply. Nutrient transfer to the foetus occurs via both active and passive transport. In case of adverse pregnancy situations, such as those involving maternal diabetes or obesity, can increase or decrease levels of nutrient transporters in the placenta resulting in overgrowth or restricted growth of foetus.
Oxygen passes from the maternal blood to the foetal blood through the placenta and carbon dioxide passes from the foetus to the maternal blood through the placenta.
The waste products excreted from the foetus such as urea, uric acid, and creatinine are all transferred to the maternal blood by the process of diffusion across the placenta.
The placenta functions as a selective maternal-fetal barrier against the transmission of microbes. IgG-antibodies can pass through the human placenta, thereby providing protection to the foetus. This transfer of antibodies begins as early as the 20th week of gestation and certainly by the 24th week. However, insufficiency in this function may still cause mother-to-child transmission of infectious diseases.
The placenta stores, glycogen, fat, etc.
6. Endocrine Function:
During pregnancy, a woman’s hormones go through many significant changes. Hormones have a very important role in the human body, especially during pregnancy. Hormones help the body function and change by causing communication from organs to tissues throughout the body. Hormones regulate the body physiologically and in other ways, including digestion, metabolism, respiration, tissue function, sensory perception, sleep, excretion, lactation, stress, growth and development, movement, reproduction, and mood. The excretion of hormones is affected by other hormones, mental activity, environmental changes, and the concentrations of ions or nutrients throughout the bloodstream. Hormones aid in metabolism regulation, immune system changes, cravings, reproductive changes, etc. The placenta, among many of its other functions, also secretes hormones that are essential to fetal life.
(a) Role of Human Chorionic Gonadotropin Hormone: The first hormone released by the placenta is called the Human Chorionic Gonadotropin Hormone (HCG). This is responsible for stopping the process at the end of menses when the Corpus luteum quits working and atrophies. If hCG did not interrupt this process, it would lead to spontaneous abortion of the foetus. The corpus luteum also produces and releases progesterone and oestrogen, and hCG stimulates it to increase the amount that it releases. hCG is also what is the indicator of pregnancy, and the hormone that pregnancy tests look for. These tests will work when menses has not occurred or after implantation has happened on days seven to ten. hCG may also have an anti-antibody effect, protecting it from being rejected by the mother’s body. hCG also assists the male fetus by stimulating the testes to produce testosterone, which is the hormone needed to allow the sex organs of the male to grow.
(b) Role of Progesterone: Progesterone helps the embryo implant by assisting passage through the fallopian tubes. It also affects the fallopian tubes and the uterus by stimulating an increase in secretions necessary for fetal nutrition. Progesterone, like hCG, is necessary to prevent spontaneous abortion because it prevents contractions of the uterus, and is necessary for implantation.
(c) Role of Oestrogen: Oestrogen is a crucial hormone in the process of proliferation. This involves the enlargement of the breasts and uterus, allowing for the growth of the foetus and the production of milk. Oestrogen is also responsible for increased blood supply towards the end of pregnancy through vasodilation. The levels of oestrogen during pregnancy can increase so that they are thirty times what a non-pregnant woman’s mid-cycle estrogen level would be.
(d) Role of Human Placental Lactogen: Human placental lactogen (hPL) is a hormone used in pregnancy to develop foetal metabolism and general growth and development. Human placental lactogen works with Growth hormone to stimulate insulin-like growth factor production and regulate intermediary metabolism. In the fetus, hPL acts on lactogenic receptors to modulate embryonic development, and metabolism and stimulate the production of IGF, insulin, surfactant, and adrenocortical hormones. hPL values increase with multiple pregnancies, intact molar pregnancy, diabetes, and Rh incompatibility. They are decreased with toxemia, choriocarcinoma, and placental insufficiency.
7. As a barrier:
Placenta serves as an efficient barrier and allows those materials to pass into the foetal blood that is necessary. The placenta and foetus may be regarded as a foreign allograft inside the mother and thus must evade attack by the mother’s immune system. However, the placental barrier is not the sole means to evade the immune system, as foreign foetal cells also persist in the maternal circulation, on the other side of the placental barrier.
8. Other Functions:
The placenta also provides a reservoir of blood for the foetus, delivering blood to it in case of hypotension and vice-versa, comparable to a capacitor.
Some steroid hormones are found in the placenta but not in foetus. Some other steroid hormones are found in foetus but not in the placenta. Hence they both work together as a fetal-placental unit to complete the hormonal system.
The duration of pregnancy in human beings is about 9 months ± 7 days which is also called the gestation period. At the end of the pregnancy vigorous contraction of the uterus causes delivery or expulsion of the foetus. The act of expelling the full-term young one from the mother’s uterus at the end of the gestation period is called parturition.
Stages of Labour
Labor pains are divided into three stages:
1. Stage of Dilation:
Early in labour, uterine contractions or labour pains, occur at intervals of 20-30 minutes and last about 40 seconds. They are then accompanied by slight pain. The time from the onset of labour pain to the complete dilation of the cervix is called the stage of dilation. This stage lasts 6-12 hours. During this stage regular contraction of the uterus, usually rupture the amniotic sac and complete dilation of the cervix occurs. The amniotic fluid flows out through the vagina.
As labour progresses. those contractions become more intense and progressively increase in frequency until, at the end of the first stage, when dilation is complete, they recur about every three minutes and are quite severe. With each contraction, a twofold effect is produced to facilitate the dilation, or opening, of the cervix. Because the uterus is a muscular organ containing a fluid-filled sac called the amnion (or “bag of waters”) that more or less surrounds the child, contraction of the musculature of its walls should diminish its cavity and compress its contents. Because its contents are quite incompressible, however, they are forced in the direction of least resistance, which is in the direction of the isthmus, or upper opening of the neck of the uterus, and are driven, like a wedge, farther and farther into this opening.
In addition to forcing the uterine contents in the direction of the cervix, shortening of the muscle fibers that are attached to the neck of the uterus tends to pull those tissues upward and away from the opening and thus adds to its enlargement. By this combined action each contraction of the uterus not only forces the amnion and fetus downward against the dilating neck of the uterus but also pulls the resisting walls of the latter upward over the advancing amnion, presenting part of the child.
In spite of this seemingly efficacious mechanism, the duration of the first stage of labor is rather prolonged, especially in women who are in labor for the first time. In such women, the average time required for the completion of the stage of dilatation is between 13 and 14 hours, while in women who have previously given birth to children, the average is 8 to 9 hours. Not only does previous labor tend to shorten this stage, but the tendency often increases with succeeding pregnancies, with the result that a woman who has given birth to three or four children may have a first stage of one hour or less in her next labor.
The first stage of labour is notably prolonged in women who become pregnant for the first time after age 35 because the cervix dilates less readily. A similar delay is to be anticipated in cases in which the cervix is extensively scarred as a result of previous labor, amputation, deep cauterization, or any other surgical procedure on the cervix. Even a woman who has borne several children and whose cervix, accordingly, should dilate readily may have a prolonged first stage if the uterine contractions are weak and infrequent or if the child lies in an inconvenient position for delivery and, as a direct consequence, cannot be forced into the mother’s pelvis.
On the other hand, the early rupturing of the amnion often increases the strength and frequency of the labour pains and thereby shortens the stage of dilatation; occasionally, premature loss of the amniotic fluid leads to the molding of the uterus about the child and thereby delays dilatation by preventing the child’s normal descent into the pelvis. Just as an abnormal position of the child and molding of the uterus may prevent the normal descent of the child, an abnormally large child or an abnormally small pelvis may interfere with the descent of the child and prolong the first stage of labour.
2. Stage of Expulsion:
The time from complete cervical dilation to delivery of the foetus is the stage of expulsion. It lasts 10 minutes to several hours. The baby passes through the cervix and vagina & is born. About the time that the cervix becomes fully dilated, the amnion breaks, and the force of the involuntary uterine contractions may be augmented by voluntary bearing down efforts of the mother. With each labour pain, she can take a deep breath and then contract her abdominal muscles. The increased intra-abdominal pressure thus produced may equal or exceed the force of the uterine contractions. These bearing-down efforts may double the effectiveness of uterine contractions.
As the child descends into and passes through the birth canal, the sensation of pain is often increased. This condition is especially true in the terminal phase of the stage of expulsion when the child’s head distends and dilates the maternal tissues as it is being born.
(a) Foetal presentation and passage through the birth canal:
(i) The manner in which the child passes through the birth canal in the second stage of labour depends upon the position in which it is lying and the shape of the mother’s pelvis. The sequence of events described in the following paragraphs is that which frequently occurs when the mother’s pelvis is of the usual type and the child is lying with the top of its head lowermost and transversely placed and the back of its head (occiput) directed toward the left side of the mother. The top of the head, accordingly, is leading, and its long axis lies transversely.
(ii) The force derived from the uterine contractions and the bearing-down efforts exerts pressure on the child’s buttocks and is transmitted along the vertebral column to drive the head into and through the pelvis. Because of the attachment of the spine to the base of the skull, the back of the head advances more rapidly than the brow with the result that the head becomes flexed (i.e., the neck is bent) until the chin comes to lie against the breastbone. As a consequence of this flexion mechanism, the top of the head becomes the leading pole and the ovoid head circumference, that entered the birth canal is succeeded by a smaller, almost circular circumference, the long diameter of which is about 2 centimeters (0.75 inches) shorter than that of the earlier circumference.
(iii) As the head descends more deeply into the birth canal, it meets the resistance of the bony pelvis and of the sling-like pelvic floor, or diaphragm, which slopes downward, forward, and inward. When the back of the head, the leading part of the child, is forced against this sloping wall on the left side, it naturally is shunted forward and to the right as it advances. This internal rotation of the head brings its longest diameter into relation with the longest diameter of the pelvic outlet and thus greatly assists in the adaptation of the advancing head to the configuration of the cavity through which it is to pass.
(iv) Further descent of the head directly downward in the direction in which it has been traveling, is opposed by the lower portion of the mother’s bony pelvis, behind, and the resisting soft parts that are interposed between it and the opening of the vagina. Less resistance, on the other hand, is offered by the soft and dilatable walls of the lower birth canal, which is directed forward and upward. The back of the child’s head accordingly advances along the lower birth canal, distending its walls and dilating its cavity while the head progresses. Soon the back of the child’s neck becomes impinged against the bones of the pelvis, in front, and the chin is forced farther and farther away from the breastbone. Thus, as an extension (bending of the head backward) takes the place of flexion, the occiput, brow, eye sockets, nose, mouth, and chin pass successively through the external opening of the lower birth canal and are born.
(v) The neck, which was twisted during internal rotation of the head, untwists as soon as the head is born. Almost immediately after its birth, therefore, the top of the head is turned toward the left and backward.
(vi) As the child’s lower shoulder advances, it meets the sloping resistance of the pelvic floor on the right side and is shunted forward and to the left toward the middle of the pelvis in front. This position brings the long diameter of the shoulder circumference into relation with the anteroposterior, or long diameter, of the pelvic cavity. Because of this internal rotation of the shoulders, the top of the head undergoes further external rotation backward and to the left so that the child’s face comes to look directly at the inner aspect of the mother’s right thing.
(vii) Soon after the shoulders rotate, the one in front appears in the vulvovaginal orifice and remains in this position while the other shoulder is swept forward by a lateral bending of the trunk through the same upward and forward curve that was followed by the head as it was being born. After this shoulder is delivered, the shoulder in front and the rest of the child’s body are expelled almost immediately and without any special mechanism. An average of about one hour and 45 minutes is required for the completion of the second stage of labour in women who give birth for the first time. In subsequent labours the average duration of the stage of expulsion is somewhat shorter.
(b) Other Foetal Presentations:
(i) Posterior Presentation: The child may lie so that the back of its head is directed backward and toward either the right or left side. The leading pole is then in the right or left posterior quadrant of the mother’s pelvis, and the presentation is referred to as the occiput anterior position. In such cases, the back of the child’s head usually rotates to the front of the pelvis, and labour proceeds in transverse positions. Because of the longer rotation required, labour may be somewhat more prolonged than in transverse positions.
(ii) Face Presentation: When the child’s head becomes bent back (extended) so that it enters and passes through the pelvis face first, the condition is known as a face, or cephalic, presentation. The chin is then the leading pole and follows the same course that is followed by the back of the head in occipital presentations. If the chin lies to the front as it enters the pelvis, labour often is easy and of short duration. Should it be directed backward, on the other hand, considerable difficulty may be encountered, and the head may have to be flexed or rotated artificially.
(iii) Breech presentation: Passage of the lower extremities or the buttocks through the pelvis first, called breech presentation, is encountered in 3 to 4 percent of deliveries. Because the head in such cases is the last part of the child to be delivered and because this part of the delivery is the most difficult, the umbilical cord may be compressed while the aftercoming head is being born, with the result that the child may be asphyxiated. Asphyxia or injuries to the child that result from the attendant’s effort to hasten the delivery in order to prevent the child’s asphyxiation are responsible for the loss of three times as many breech babies as head-on babies. For this reason, the child may need to be manipulated into a head-on position by the attendant or be delivered by a surgical procedure called cesarean section.
The infant mortality rate in developed countries varies from 2 to 10 percent according to the size of the child and the skill of the attendant. Because very small premature infants are particularly susceptible to the dangers of breech delivery, the mortality among them is very high when they are born breech first.
(iv) Transverse Presentation: In this relatively rare situation the long axis of the child tends to lie across, or transverse to, the long axis of the mother. Unless the child is very small, delivery through the natural passages is impossible in such cases; therefore, delivery by cesarean section is necessary. Because the above-mentioned complications are infrequent and can be cared for easily, the maternal death rate is less than 1 per 1,000 and would be still lower if the deaths caused by complicating systemic diseases were excluded. The infant mortality rate is also low, ranging between 1.5 and 3 percent. It would be much lower if premature and poorly developed infants were excluded. In other words, the risk to a healthy mother who carries her child to maturity is less than 1 per 1,000, and the risk to her mature child is about 0.5 percent.
3. Placental Stage
The time after delivery, until the placenta is expelled by powerful uterine contraction, is the placental stage. In about 28-35 days, the uterus returns fully to its non-pregnant state: With the expulsion of the child, the cavity of the uterus is greatly diminished. As a consequence, the site of placental attachment becomes markedly reduced in size, with the result that the placenta (afterbirth) is separated in many places from the membrane lining the uterus. Within a few minutes, subsequent uterine contractions complete the separation and force the placenta into the vagina, from which it is expelled by a bearing-down effort. The third stage of labour, accordingly, is of short duration, seldom lasting longer than 15 minutes. Occasionally, however, the separation may be delayed and accompanied by bleeding, in which case surgical removal of the placenta is necessary.
Hormonal Control in Parturition
In parturition, hormones play a major role. We discuss the role of several hormones in the following:
- Oxytocin: It secretes from the foetus and mother’s posterior pituitary. It stimulates the uterus to contract. It also causes powerful contractions of myometrium during parturition.
- Prostaglandin: It stimulates more contractions of the uterus.
- Relaxin: It causes the aidening of the pelvis by relaxing the pubic symphysis of the pelvic girdles.
- Oestrogen: This hormone is secreted from the ovaries and induces oxytocin receptors in the uterus.
To determine pregnancy, a pregnancy test has been done. According to the indication of certain markers, pregnancy can be detected in urine. A pregnancy test requires sampling one of these substances. Human chorionic gonadotropin (hCG) is a reliable marker of pregnancy. A pregnancy test measures a hormone in the body i.e., hCG which is produced during pregnancy. It appears in the blood and urine of pregnant women as early as 10 days after conception. The presence of hCG is determined by using an immunological technique. This technique is based on double antigen-antibody reactions. This type of technique is commonly used for detecting pregnancy and is named as Gravindex test.
To determine the agglutination of HCG-coated latex.
Firstly one drop of HCG antiserum is taken in a glass slide. Next, a drop of urine from the woman, who is suspected to be pregnant is taken in the same slide. Both are mixed thoroughly. If the urine of the woman contains HCG all the antibodies of the antiserum get used up easily for the agglutination of HCG molecules. Now, one drop of latex is added to this mixture.
If the urine of the woman contains HCG then the HCG of antiserum is fully agglutinated with it and no free antibody is available for further reaction with hCG-coated latex buds. In this way the absence of agglutination of latex buds confirms pregnancy. But if the urine sample does not contain hCG then the antiserum is available to bind with hCG-coated latex. So then the agglutination of latex indicates that the woman is not pregnant.
Types of Pregnancy Tests
A pregnancy test is done using blood or urine. There are 2 types of blood tests:
- Qualitative, which measures whether the hCG hormone is present.
- Quantitative, which measures how much hCG is present.
The blood test is done by drawing a single tube of blood and sending it to a laboratory. You may wait anywhere from a few hours to more than a day to get the results. The urine hCG test is usually performed by placing a drop of urine on a prepared chemical strip. It takes 1 to 2 minutes for a result.
Utility of Pregnancy Test
- This test is done to determine if anyone is pregnant.
- To diagnose abnormal conditions that can raise the hCG levels.
- To watch the development of the pregnancy during the first 2 months (by Quantitative Test).
The production of milk in the mammary glands is called lactation.
The mammary glands of women undergo differentiation during pregnancy and start producing milk towards the end of the pregnancy and after the birth of the baby.
Role of Hormones
At puberty, a female’s mammary glands begin to develop under the influence of oestrogen and progesterone. Secretion of milk generally begins after birth usually 24 hours under the influence of prolactin secreted by the anterior pituitary. However, the ejection of milk is stimulated by the oxytocin released from the posterior pituitary.
Milk ejection in lactating mothers is a neurohormonal reflex process. The receptors for this reflex are present at the nipple and areolar tissue of the mammary gland. These receptors are mainly mechanical touch receptors. When these receptors are stimulated by through the surface of the baby’s tongue. The afferent impulse came to the hypothalamus via the spinothalamic tract and stimulates the supraoptic nucleus (SON) and the Para ventricular nucleus (PVN). Both these nuclei help to release oxytocin from the posterior pituitary into the blood. Here the hypothalamus acts as a center.
Blood acts as the efferent path of this reflex, carrying oxytocin to the mammary gland which is the effector organ of this reflex action. Stimulation of myoepithelial cells of alveoli occurs by this reflex. And ultimately milk is drained from the alveoli into the baby’s mouth through the lactiferous duct and galactopore.
The first milk comes from the mammary glands of the mother just after childbirth. Colostrum is rich in protein and low fat. Colostrum contains antibodies (IgA) that provide passive immunity to the newborn infant.
Composition of Human Milk and Colostrum:
|Colostrum (gm%)||Mature Milk (gm%)|
|1. Proteins||8.5||1 – 2|
|2. Fat||2.5||3 – 5|
|3. Carbohydrate (Lactose)||3.5||6.5 – 8.5|
|4. Minerals (Na+, K+, P+, and Cl-)||0.35||0.18 – 0.25|
Importance of Breast Feeding
Breastfeeding is advised by doctors from all over the world. It gives advantages to both baby and the mother.
Advantages for the Baby:
- It is a naturally balanced diet (containing all 6 food groups) for the baby.
- It protects the baby from infections as it possesses immunoglobulin, lymphocytes, lysozyme, etc.
- Human milk is easily digestible by its digestive properties.
- Various growth-promoting factors such as epidermal growth factors, and insulin are present in human milk.
- It is sterile and inexpensive. Chances of allergy to breast milk are rare.
Advantages to Mother:
- This is the natural way of contraception and birth spacing.
- It gives protection against obesity because body fat is used for milk synthesis.
- Prolonged lactation provides protection against breast cancer.
- Breastfeeding creates an emotional bonding between mother and child.
- Oxytocin released during lactation acts on the uterine myometrium and helps it to inoculate for this period.