Much of what's happening to your body now that you're pregnant — both the good and the not-so-good — can be traced to hormones. The truth is, this potent cocktail of chemicals can cause everything from blemishes and bloating to pregnancy brain and mood swings. Of course, pregnancy hormones are also doing the incredible job of supporting your pregnancy and preparing for breastfeeding.
"Crying and being mad at my husband are the two things I'm good at these days," jokes What to Expect Community mom bababy327.
Read on to learn which hormones are most important and what roles they play in your pregnancy.
What are the main pregnancy hormones?
The following hormones are key players that help get pregnancy started and prepare your body for labor and delivery.[1] Each has its own job to fill before, during, and after pregnancy.
- Estrogen
- Progesterone
- FSH (follicle-stimulating hormone)
- LH (luteinizing hormone)
- hCG (human chorionic gonadotropin)
- Prolactin
- Placental growth factor
- HPL (human placental lactogen)
- Relaxin
- Oxytocin
Here's a look at what each of these hormones does.
What is estrogen?
Estrogen is the main female hormone responsible for sexual development, including breast growth, and it kickstarts and regulates your menstrual cycle. It also helps to keep your bones strong and cholesterol levels in check.[2]
Along with progesterone, estrogen is one of the two main hormones that get the pregnancy party started. Produced by the ovaries and later by the placenta, estrogen helps the uterus grow, maintains the uterine lining, regulates other key hormones, and supports the development of your baby's organs. When it's time to breastfeed, estrogen also promotes the growth of breast tissue and supports milk flow.
Got a stuffy nose — or blotchy skin? Estrogen contributes to swollen mucous membranes and increases blood flow to your skin, which can result in redness or itchiness. It also plays a role in hyperpigmentation, causing darker nipples and brown patches (melasma) on the face.[3]
"I have so many dark patches on my cheeks, upper lip, and chin!" says Community member Ariella123456.
Track your pregnancy journey through every stage, and connect and share with other pregnant moms in the What to Expect app.
What is progesterone?
Progesterone, produced mainly in the ovaries after ovulation, works alongside estrogen as one of the "big two" pregnancy hormones. It helps prepare the uterine lining for implantation of a fertilized egg and supports early pregnancy.
Along with the hormone relaxin, progesterone can slow digestion, leading to symptoms like heartburn, indigestion, constipation, and bloating. The combination of progesterone and relaxin also helps soften ligaments and cartilage and loosens your joints to prepare you for labor.
And if your gums swell and start to bleed, your skin breaks out, or you feel super sweaty, that's the handiwork of this hormone, too.
"My gums have gotten so irritated and sensitive to anything, including a simple bite from an apple," says Community member EliMarie97.
What is follicle-stimulating hormone (FSH)?
Follicle-stimulating hormone (FSH), produced by the pituitary gland, is part of a cascade of hormones that's necessary to launch your pregnancy and is present before you even conceive.
It stimulates egg development in the ovaries, which increases estrogen production. Rising estrogen levels then signal the body to produce a surge of luteinizing hormone (LH), leading to ovulation and potentially pregnancy.
Interesting fact: Women who have fraternal twins tend to have higher levels of FSH.
What is luteinizing hormone (LH)?
This hormone, also produced by the pituitary gland, works in concert with FSH to orchestrate your menstrual cycle. LH levels rise just before ovulation, triggering the release of an egg from the ovary. After ovulation, the follicle forms the corpus luteum, which produces hormones like progesterone to support a potential pregnancy.
If fertilization doesn't occur, the corpus luteum breaks down, hormone levels drop, and your period begins. If pregnancy does occur, it continues producing hormones to support early development.
Your doctor may check your LH levels if you're having trouble conceiving, since imbalances can affect ovulation and may be linked to conditions like polycystic ovarian syndrome (PCOS).[4]
What is human chorionic gonadotropin (hCG)?
Human chorionic gonadotropin (hCG) is often called the pregnancy hormone because it's only produced during pregnancy.[5]
This hormone ramps up the production of estrogen and progesterone, and it's the hormone detected by home pregnancy tests. Early in pregnancy, hCG levels rise rapidly, doubling every couple of days before peaking between week 7 and week 12, then declining at the start of your second trimester.
This hormone also plays a role in suppressing the immune system, sometimes leaving you more vulnerable to colds and the flu.
What is prolactin?
Prolactin is another hormone that's made by the pituitary gland, and it's essential for milk production.[6] Its main job is to prepare your breasts for breastfeeding and stimulate milk production after your baby is born.
Prolactin also stimulates the adrenal glands, which can trigger new hair growth in unexpected places (such as on the belly and face), though this fuzz usually disappears around six months postpartum.
What is placental growth factor?
Placental growth factor helps stimulate blood vessel growth, which transports the increased blood volume needed to nourish and support a growing baby.
Low levels of this pregnancy hormone may cause blood vessels in the placenta to narrow instead of widen, which may be linked to complications such as high blood pressure and preeclampsia. Fortunately, blood and urine tests can help monitor levels for early detection and treatment.
What is human placental lactogen (hPL)?
Human placental lactogen, sometimes called human chorionic somatomammotropin, is produced by the placenta and helps regulate your metabolism to support your baby's growth.
The "lact" part of the name hints at its role in milk production: It helps prepare your breasts for breastfeeding and supports the production of colostrum, the nutrient-rich early milk.
In some cases, hPL and placental growth factor may contribute to insulin resistance, which can lead to gestational diabetes.
What is relaxin?
Relaxin plays a big role in a woman's reproductive process. Levels rise after ovulation and help prepare the uterine wall for pregnancy. If fertilization doesn't occur, levels drop until the next cycle.
If you do conceive, relaxin lives up to its name by helping relax your muscles, bones, ligaments, and joints in preparation for labor. It also softens and lengthens the cervix. These changes can sometimes make you feel off balance and wobbly as you walk (be careful!).
"I feel like certain joints are shifting wonky, and I'm more sore and out of alignment," says Community member brcarr.
"I tripped on my outdoor stairs and rolled my ankle!" says Community mom ElleBellebear. "I've never fallen like that before and now I'm super cautious."
What is oxytocin?
Oxytocin, produced by the hypothalamus and released by the pituitary gland, plays a key role in labor and delivery.
Though present throughout your pregnancy, this muscle-contracting hormone is best known for stimulating labor contractions. If labor is slow to progress, you might receive Pitocin, a synthetic version of oxytocin, to help move things along. After delivery, oxytocin helps shrink the uterus and move milk into the breasts.
Are there other pregnancy hormones?
Yes, there are even more hormones at work during pregnancy, including:
- Erythropoietin: Regulates red blood cell production.
- Calcitonin: Promotes bone formation.
- Vasopressin: Regulates fluid balance. High levels can lead to water retention.
- Thyroxine: Increases oxygen consumption, supports fetal growth, and helps develop the baby's central nervous system.
- Insulin: Controls metabolism in both mother and baby.
- Adrenocorticotropic hormone: Triggers adrenal glands to release hormones that contribute to stretch marks and swelling.
- Cortisol: Aids in fetal lung maturation. In high concentrations, this stress hormone may interfere with progesterone and contribute to brain fog.
- Endorphins: Reduce stress and pain. These natural feel-good hormones may help you cope with labor pain — and perhaps even forget it once you meet your sweet new baby.
Are there postpartum hormones?
Even after labor and delivery, your body is awash in hormones. While progesterone and estrogen drop quickly after your baby arrives, oxytocin (sometimes called the "mothering hormone") and prolactin remain elevated to support bonding and breastfeeding.
This roller coaster mix of postpartum hormones can be tough for some new moms, potentially leading to irritability, tears, and the baby blues. These feelings are common, affecting up to 80% of new mothers. If you feel sad or out of sorts after the birth of your baby, talk with your doctor.[7]
"Dealing with the hormone crash is something nobody can prepare for," says Community mom KM201318. "At least with my second and third baby I knew what to expect."
"There's not much you can do while waiting for hormones to balance, but I tried to sleep as much as possible and had the support system for it," says Community mom liztambo.
Some of these pregnancy hormones may seem like alphabet soup at first, but they're actually a powerful group of chemicals working hard on your behalf.
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