A Simple Guide to Pregnancy Hormones

Hormones has both its good and bad. This comprehensive guide gives you an insight on how hormones help you pre, during and post pregnancy!

What are the main pregnancy hormones?

Every hormone experienced before, during and after pregnancy serves its own purpose but these are the hormones responsible for preparing your body for labour and delivery.

● Follicle-stimulating hormone (FSH)

● LH (Luteinizing Hormone)

● hCG (Human Chorionic Gonadotropin)

● Estrogen

● Progesterone

● Relaxin

● Placental growth factor

● HPL (Human Placental Lactogen)

● Oxytocin

● Prolactin


As the main female hormone contributor to sexual development, estrogen is involved in the growth of the breasts and regulates a woman’s menstrual cycle. Furthermore, it also keeps your bones healthy and cholesterol levels in check.

What does estrogen do during pregnancy?

Estrogen is produced by the ovaries and later by the placenta to help the uterus grow, maintain the uterine lining, regulate other key hormones and trigger the development of the baby’s organs. When breastfeeding is due, estrogen promotes the growth of breast tissue and helps milk flow.

Not limited to that, they are also behind swollen mucous membranes and are the cause of red and itchy complexion as extra blood flows to your skin. When joined by other hormones, it also causes hyperpigmentation in the nipples and brown patches on the nose, cheeks and forehead.


After each monthly ovulation, progesterone is made - mostly in the ovaries - to help regulate your next menstrual cycle alongside the help of estrogen.

What does progesterone do during pregnancy?

As one of the main female hormones, progesterone gets to work shortly after ovulation by preparing the uterine lining for the implantation of a fertilised egg.

During pregnancy, it can cause some trouble such as heartburn, indigestion, constipation and bloating. Swelling and bleeding in the gums, sweaty and breaking in the skin is also the work of this particular hormone too.

But when teamed up with another hormone, relaxin, it helps soften ligaments and cartilage, and loosen the joints to prepare women for labour.

Follicle-Stimulating Hormone (FSH)

FSH is formed by the pituitary gland in the brain that directs the ovaries to produce eggs and estrogen. In other terms, FSH controls the monthly cycle.

What does FSH do during pregnancy?

FSH is necessary to launch a pregnancy and is present in the body even before a baby is conceived. It further stimulates eggs tog row in the ovaries which in return, increases the production of estrogen. Rising levels of estrogen signal the body to produce a surge of LH which brings about ovulation and potential pregnancy.

Luteinizing Hormone (LH)

Together with FSH, LH is made by the pituitary gland to orchestrate the menstrual cycle. LH levels rise just before ovulation and trigger the release of an egg from your ovary.

While LH prompts the production of estrogen, estrogen will call on LH to burst the follicle and free up an egg. The post-ovulatory follicle creates the corpus luteum that disintegrates in about 14 days if you are not pregnant, at which point your hormone levels will drop and your period will arrive.

What does LH do during pregnancy?

When a sperm successfully fertilises an egg, the corpus luteum lives on to produce the right hormones that will continue to ripen the uterus and nourish your growing baby.

Couples who find it difficult to conceive will have their LH levels checked when at the doctor. Levels that are higher than normal may impact ovulation. news.

Human Chorionic Gonadotropin (hCG)

hCG is only produced during pregnancy and amps up the production of estrogen and progesterone.

What does hCG do during pregnancy?

hCG is what gives you a positive result when taking a home pregnancy test. Early into the pregnancy, hCG levels are low but rise and double every two days between weeks 7 and 12. At the start of your second trimester, it will fall back again.

Though the placenta will start making estrogen and progesterone, hCG is here to stay. This affects the immune system and leaves pregnant women more vulnerable to colds and flu.


Another hormone created by the pituitary gland, prolactin is mainly responsible for lactation.

What does Prolactin do during pregnancy?

Prolactin enlarges the breasts and produces the milk needed to feed the baby. It also triggers new hair growth such as the stomach and face (no worries as the fuzz should disappear around 6 months postpartum!) by charging up the adrenal glands.

Placental Growth Factor

The placental growth factor encourages blood vessel growth which in turn transports the increased blood volume needed to nourish and support a growing fetus.

What does Placental Growth do during pregnancy?

A lack of this pregnancy hormone may cause blood vessels in the placenta to narrow instead of widening. This could lead to high blood pressure and possibly preeclampsia.

With the advancement in medicine, new blood and urine tests can now measure placenta growth factors for early detection and treatment.

Human Placental Lactogen (HPL)

Just like prolactin, hPL is connected to milk production in an expecting woman’s body.

What does hPL do during pregnancy?

hPL is produced by the placenta to adjust your body’s metabolism to feed your baby. Together with the placental growth factor, it prepares the breasts for breastfeeding. hPL helps to produce colostrum which is an antibody-rich pre-milk that precede the actual breast milk.

In some women, hPL and the placental growth factor are thought to lead to insulin resistance, resulting in gestational diabetes.


Playing an important role in a woman’s reproductive process, relaxin levels rise after ovulation and prepare the uterine wall for pregnancy. If no fertilisation occurs, relaxin levels drop back down until the next cycle approaches.

What does relaxin do during pregnancy?

If an egg is successfully fertilised, relaxin helps with relaxation in the muscles, bones, ligaments and joints in the pelvis for later on in the pregnancy. It also softens and lengthens the cervix though its limbering mechanism may make one feel off-balanced and wobbly when in motion.


Oxytocin is produced by the hypothalamus before being secreted by the multi-functioning pituitary gland. In particular, oxytocin is critical when it comes to labour and delivery.

What does oxytocin do during pregnancy?

Oxytocin is present throughout the entirety of pregnancy and is otherwise known as the muscle-contracting hormone which stimulates labour contractions. If progress is slow during labour, one may receive a shot of Pitocin - the synthetic version of Oxytocin - to help speed things along.

After delivery, oxytocin will help shrink the uterus down in size and transport milk into the breasts.

Postpartum Hormones

The body will still be coursing with hormones even after labour and delivery. While estrogen and progesterone see a drop after the arrival of your baby, oxytocin and prolactin see an increase.

The mix of postpartum hormones can be tough for new moms and bring about many rounds of irritability, tears and baby blues. Just know that these feelings and normal and are not uncommon.

Should you feel sad or out of sorts after giving birth, speaking to a doctor or a trusted confidant is a good way to overcome the feeling! You got this, Momma 💛


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