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Hormones During Pregnancy, Labour and Lactation

During the different stages of a women’s maternal journey, there are a wide range of hormones that come together to work in such perfect harmony; each one with its own unique function. These hormones, working together, help with a variety of factors such as:
• Sustaining a pregnancy
• Estimating the number of embryos present
• Lactation
• Bonding
• Breast, fetal and physiological development
• Preparing one for parenthood
• Progressing labour
• Relieving labour pain

Below is a detailed break down of the 10 most important maternal hormones, how they function and what their roles are during the maternal period (from pregnancy through to lactation).

1. Human Chorionic Gonadotropin

The Pregnancy Hormone

hCG (Human Chorionic Gonadotropin) is a very special hormone that is secreted by the developing placenta of the embryo in the very early stages of pregnancy. This is the hormone that is responsible for disclosing the news of a new life on your pregnancy test: a positive result!

hCG has a very special function during these first few weeks of pregnancy, a function so vital that without it, the embryo would have no way of maturing. hCG stimulates the corpus luteum on the ovaries, causing them to release higher doses of progesterone into the body, which is vital for the maintenance of the endometrium (uterine lining) which accommodates and nourishes the embryo. Without this lining, the embryo would have no where to adequately implant in order to grow.

By measuring the levels of hCG in a woman’s blood, a doctor can get an idea of a woman’s gestation; how many weeks pregnant she is. Higher levels of hCG may also be able to indicate the possibility of multiple embryos due to the extra number of placentas producing this hormone, whereas lower levels of hCG may indicate the possibility of a miscarriage.

When you see those two little lines smiling back at you on a pregnancy test, you know who is to blame (apart from you and your partner of course).

2. Oxytocin

The Love and Bonding Hormone

Oxytocin is a social hormone, released during social interactions that create a “bonding” type of experience, hence it being nicknamed the ‘love’ or ‘bonding’ and even the ‘cuddle’ hormone.
Oxytocin can be released during various types of interactions, but there are three specific social interactions that produce the highest levels of this hormone in a person’s life: sex, childbirth and breastfeeding.

Oxytocin holds many functions in social interactions (such as a person’s decision to accept/reject another; influencing a persons level of attraction and even their choice of fidelity) but this hormone, in maternal women, has two main functions: contracting the uterus and stimulating the let-down reflex during lactation.

During labour, oxytocin levels gradually increase as the labour progresses to promote stronger contractions; it also stimulates the production of prostaglandins to assist with the softening of the cervix allowing it to thin and open.
Oxytocin, in it’s naturally produced form (not artificially, through inductions) acts as a pain reliever during contractions by stimulating the production of endorphins in the body. Natural oxytocin is also responsible for keeping a foetus calm in utero during the physical demands of labour, especially during contractions, minimizing foetal distress.

During the pushing stage of labour, the mother receives a massive oxytocin rush, probably the highest she will experience in her life. This ‘rush’ allows her the ability to birth her baby with ease, due to the intense contractions and the blocking of pain. It prepares the body for the expulsion of the placenta and the immediate shrinking of the uterus postpartum to prevent the mother hemorrhaging. This oxytocin ‘rush’ also prepares the setting of euphoria that the mother and baby will feel in the first hour after birth (also known as the golden hour) so that mother and child can effectively bond, rewiring both brains into a state of maternal instinct (mother) and emotional dependency (infant).

Skin-to-skin between mother and baby promotes the production of oxytocin, increasing the success of breastfeeding, which in itself also promotes oxytocin production. During breastfeeding, the infant’s suckling at the nipple stimulates nerves which cause the brain to release oxytocin; this release of hormone stimulates the mother’s let-down reflex, which brings the milk down the milk ducts and forward to the nipple. It also increases the bonding of mother and child during the breastfeeding stage, increasing the mother’s maternal state while bringing a sense of security to the newborn.

From sex, to breastfeeding, and the childbirth process in between, it’s oxytocin that plays the biggest role as it bonds, comforts and empowers! What a truly magnificent hormone!

3. Endorphins

The Relief Chemicals

Endorphins, also known as the body’s natural morphine, are specialised chemicals that are produced by the brain and the nervous system during times of stress, pain and over exertion; these are the body’s ‘coping’ chemicals as they bring relief and help one cope.

Endorphins, once released, stimulate and trigger the brains opiate receptors, giving a person an ‘opium’ like high. This ‘high’ is a non-psychedelic experience, that blocks pain (more effectively than opiate drugs), alters one’s perception of time and place, and creates a general state of calm and well being.

During labour, these specialised chemicals are part of a beautifully balanced cycle that is vital to the birth process. Endorphins further encourage the release of oxytocin (necessary for labour progress, pain relief, protecting the foetus in utero and establishing a strong emotional foundation for mother and child after birth while ensuring successful breastfeeding) and the release of oxytocin further encourages the release of more endorphins, and so this harmonious cycle continues. Endorphins, working together with oxytocin, sets the stage for a successful, manageable and beneficial birthing experience.

The use of opiate drugs during labour (such as pethidine) does not alter the body’s endorphin production, however, epidurals do; epidurals not only block the production of endorphins, but remove endorphins from the body entirely; this interferes with the body’s ability to naturally release oxytocin during the birth process, increasing a woman’s risk of needing an induction to progress her labour.

By allowing your body to experience the pain and stress of labour, you encourage your body to respond with a natural coping mechanism in the form of endorphins, which also assists in the progression of labour. You simply must surrender to labour’s demands in order to tap into the super powers of these coping chemicals.

4. Prolactin

The Lactation Hormone

Prolactin is an astounding hormone found in both males and females, in relatively low doses, which plays a role in lactation, behavior, immunization, metabolism, reproduction and fertility. However, prolactin levels are much higher in women who are pregnant and even higher during breastfeeding.

Prolactin is a hormone that is produced by the pituitary gland; during pregnancy to stimulate the production of colostrum, and after birth to stimulate the production of breast milk. The higher the prolactin levels, the more milk a lactating woman will produce.

Another incredible function of prolactin is it’s ability to block the production of the hormones estrogen (in women) and testosterone (in men).

In woman, lowered estrogen production results in either irregular periods, or even no periods at all (this is the main reason why a breastfeeding woman generally doesn’t menstruate). It also lowers her sex drive and is responsible for vaginal dryness. These reasons are normally why breastfeeding is seen as a contraceptive. However, breastfeeding is not 100% effective in preventing pregnancy due to many other factors of breastfeeding.

Many other hormones are responsible for the release of prolactin into the bloodstream, but in breastfeeding, it is the stimulation of the nipple, caused from the infant’s suckling at the breast, along with hormonal changes after pregnancy (particularly lowered estrogen levels) that encourages the release of prolactin to produce breast milk.

5. Adrenaline

The Survival Hormone

Adrenaline is a remarkable and fascinating hormone responsible for our survival!

Secreted by the adrenal glands and nervous system in moments of fear, stress or extreme pain, this hormone rushes through the body, creating a fight-or-flight response. This response is designed in such a unique way that it’s purpose is to keep one safe from that which is unfavorable.

Now, labour means pain, and the pain of labour is a very different kind of pain with a different level of intensity. However, this is a pain that one can not from; this is a pain that demands one’s full attention to face it, head on, with all you’ve got! Which is why we can only be so incredibly grateful for adrenaline!

During the early stages of labour, when contractions are still fairly mild (compared to transitional labour) it is important that a woman remains calm. Stress during this time causes stress hormones to be released, such as adrenaline, and this tells the brain and body that it is “not favorable” or “not safe” for birth to proceed and so labour may slow down or even stop entirely. The body and mind desire a safe space to labour and birth and this sense of safety that you communicate to your body and mind is in the form of being calm and relaxed. This is nature’s beautiful way of ensuring the safety of the newborn infant and the vulnerable state of the mother directly after birth.

So, how then does adrenaline help with labour?

Adrenaline’s prime purpose reveals itself in the very last stages of labour, like a riveting grand finale! Once a woman has relaxed sufficiently in the early stages that she has effectively dilated to the transitional stage of labour, the body now knows that it’s “too late” to turn back. The intense pain of transitional labour and the pressure of the baby’s head against specific nerves in the birth canal kick starts the adrenaline response through the woman’s body; adrenaline starts to rise (assisting with the increase of the woman’s pain threshold) and when it peaks, it gives her this incredible second wind of energy, alertness, strength and will power – her FIGHT response – to face the next stage.

Her pain begins to dull and her sense of time and place leave her while her focus shifts directly towards this “urge” to push; this is the power of adrenaline in it’s prime: it allows a woman this super power ability to simply, instinctively birth her baby. Truly phenomenal!

The balance of this hormone during the birthing process is so delicate yet at the same time so powerful!

6. Prolactin

The Mothering Hormone

This hormone has many functions behind it’s name; it’s involved in metabolism, immunity, fertility, lactation and even behavior; prolactin has the power of influencing a persons behavior.

Men and women have basic sex hormones which are the foundational hormones of that specific sex… and their main function is their involvement in… sex! Men have testosterone and women have estrogen.

One of our main responsibilities as human beings is reproduction/procreation and almost all that we do revolves around being more sexually attractive in order to attract an ideal mate. But what happens if the ideal mate has already been chosen and reproduction has already taken place and a baby has now been born?

Parental instinct (maternal/paternal) is influenced by the increased levels of prolactin in a persons body after birth. Prolactin blocks the main sex hormones (estrogen and testosterone), rewiring the new parents’ brains from the purpose of sexual reproduction to that of parental responsibility by increasing alertness, willing submission and anxiety.

Lowered levels of sex hormones can also cause a decrease in one’s sex drive by causing vaginal dryness and weaker erections; sex now takes a back seat and the front seat is replaced with the instinctive call to meet the new baby’s needs. The symptoms of lowered sex hormones are stronger on the maternal side and this could likely be caused from much higher levels of prolactin, normally attributed to lactation. High levels of either estrogen or testosterone during breastfeeding can hinder the production of prolactin hormone, which can have a negative effect on milk supply and breastfeeding. This is another one of the main reasons that these sex hormones are naturally suppressed in a mother’s body during the first few months after birth; it facilitates her ability to lactate and feed her baby.

Certain contraceptives and hormone replacing drugs (drugs high in estrogen, progesterone or testosterone) can greatly suppress prolactin production, negatively affecting a woman’s ability to lactate. Such drugs should be considered wisely and cautiously if the goal is to breastfeed easily, long term and without complication. You may even want to consider alternative contraceptive options.

With the increase of prolactin and decrease in sex hormones, another symptom a mother may notice is her delayed menstrual cycle. This can be delayed for up to year after birth if a mother continues to breastfeed as much as possible, as breastfeeding continues to stimulate the production of prolactin by stimulating the release of oxytocin, which in turn suppresses the sex hormones responsible for menstruation.

So, if you ever wonder why a new parent is focused more on their baby and less on sexual desire, prolactin is the guilty culprit. However, we can also be grateful because it’s just as responsible for making sure that a baby gets the best care possible, which is vital for their safety, development, comfort and health, creating a lasting impact on the well being of the child’s life (long term).

7. Progesterone

The Female Fertility Hormone

Progesterone is a hormone that is naturally produced by a woman’s ovaries during her monthly cycle. After a woman’s menstrual cycle, the levels of progesterone will increase to start preparing the uterus for a little guest. It will begin to build and thicken the endometrium (uterine lining) making it an ideal haven for implantation; filling out a woman’s breasts in preparation for pregnancy; and puts the menstrual cycle on hold while the body eagerly anticipates the arrival of a fertilized egg.

Once a woman falls pregnant, at around roughly 9 weeks after conception, the developing placenta will begin to take over the production of progesterone with the prime purpose of maintaining an ideal environment to sustain the pregnancy.

Progesterone also helps with breast development during pregnancy, preparing them for the task of milk production and breastfeeding. The increase in progesterone levels can cause breasts to feel bigger, fuller and rather tender due to the rapid development of the breast tissues.

This hormone really is the hormone of female fertility because without it, the body would not be able to accommodate a pregnancy adequately which means there would be no element of procreation.

8. Relaxin

The Softening Hormone

Relaxin is a hormone that is released by the ovaries before pregnancy to inhibit uterine contractions which promotes the development of the endometrium so that it may properly inhabit a fertilized egg.

During pregnancy, the placenta will begin to release this hormone as well. It assists with effective implantation of the egg; development of the placenta; relaxation of the ligaments and joints to accommodate a growing uterus and rapid weight gain; inhibiting contractions to prevent miscarriage and premature birth; and assisting the blood vessels in the cardiovascular and renal systems to adequately accommodate the increase in blood volume, oxygen and waste products.

During labour and childbirth, relaxin assists with the dilation and effacement of the cervix, the rupture of the amniotic membranes, and the relaxing of the vagina and perineum allowing a smooth passage for the baby to pass through.

Without this incredible hormone, pregnancy would not exist and childbirth would be so physically traumatic it probably wouldn’t even be possible. This hormone is not only vital but truly remarkable too.

9. Testosterone

The Masculine Hormone

Testosterone is the male sex hormone produced by the adrenal glands and sexual organs of both men and women; although, the levels of testosterone are much higher in men than in women.

This hormone is responsible for the masculine properties found in men. Study’s show that the levels of testosterone in men begin to gradually decrease from early pregnancy but levels increase in women.

It is believed that the reason for the decrease in men is to slowly prepare a man for fatherhood. These lowered levels suppress aggression and sexual desire, rewiring a man’s brain from the purpose of competition and procreation to nurturing and caring for his newborn.

In woman, a study showed that increased testosterone during pregnancy influences the growth of the foetus. The higher the levels of testosterone, the smaller the baby was presumed to be, perhaps testosterone keeps the growth of the baby balanced? These increased levels would also explain the increased body hair that many woman experience through their pregnancy.

10. Estrogen

The Fertility and Pregnancy Hormone

Estrogen is a very busy hormone that plays an active role throughout a woman’s life, and during pregnancy, a woman’s estrogen levels are the highest they’ll ever be in her entire life. In fact, it’s said that a single pregnancy will produce more estrogen than what is produced in the full life span of a non-pregnant woman.

It is produced by the ovaries before conception to build the breast tissue, assist with the growth of the uterine lining (endometrium) and regulate the menstrual cycle.

However, after conception, it takes on more responsibilities. Still produced by the ovaries during early pregnancy and later by the placenta, it develops the milk ducts in the breasts, promotes uterine growth while helping to maintain the pregnancy. It increases blood flow, regulates the production of other important hormones and assists with foetal development (specifically the organs and bone density).

It’s elevated levels lead to nausea and vomiting (morning sickness), increased sensitivity of the skin, darkened discoloration of the skin (chloasma, linea nigra, areolas), while also softening and swelling the mucous membranes leading to a blocked nose, random nose bleeds, the pregnancy ‘glow’, post nasal drip, and excessive vaginal discharge.

Estrogen really is one of the key players in female reproduction and fertility and without it, women just simply wouldn’t be, well, women.

♥   ♥   ♥

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1 thought on “Hormones During Pregnancy, Labour and Lactation

  1. Reply
    Melissa - June 22, 2021

    THIS WAS SO COOL to read through!!!

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