Your Guide to Pregnancy Hormones

What’s a hormone again? It’s a chemical message from the five glands of your endocrine system to the rest of your body. Even when you’re not pregnant, they control your appetite, sleep, sex drive. Basically everything. When you get pregnant, your pregnancy hormones turn your body into a baby maker with some fun side effects too.

What are the Main Pregnancy Hormones?

Human Chorionic Gonadotropin (HcG)

HcG is the hormone that tells the rest of your body that you’re pregnant. It’s also the indicator that over-the-counter pregnancy tests use.

What does HcG do? HcG is the most likely pregnancy hormone behind morning sickness because higher levels are correlated with more intense vomiting and nausea. Another key task: increasing production of estrogen and progesterone so they can do their part to grow the baby.

When will HcG matter? For the first two months of your pregnancy, your HcG levels will continue to rise very quickly, doubling every other day, then plateau for the rest of your pregnancy.

Progesterone

Progesterone, like estrogen, is used in birth control pills to trick your body into thinking you’re pregnant so you don’t actually get pregnant.

What does progesterone do? This hormone plays a key role in your pregnancy. During the first trimester, this pregnancy hormone makes your breasts more sensitive and helps them get ready to start making milk. It relaxes the uterus so it doesn’t reject the fetus. It contributes to feelings of bloat and fatigue.

When will progesterone matter? Progesterone levels skyrocket during the first trimester and then plateau. The placenta makes progesterone during pregnancy, so following birth when the placenta comes out along with the baby, progesterone levels fall, contributing to mood swings.

Estrogen

This pregnancy hormone is synonymous with woman. It pushed you through puberty and regulates your monthly cycle too.

What does estrogon do? During pregnancy, estrogen helps the uterus grow and jumpstarts fetal development. It also increases blood flow, which heightens your sense of smell and gives you that pregnancy “glow.” Side effects: spider veins and increased appetite.

When will estrogen matter? Estrogen levels continue to rise through your pregnancy and peak in the third trimester. Since this pregnancy hormone is also generated by the placenta during pregnancy, estrogen levels crash postpartum.

Relaxin

The name says it all.

What does relaxin do? Relaxin keeps your uterus relaxed during the first trimester and helps with the growth of your placenta. It also makes your ligaments relax. This can make you more prone to falls because you are a bit more wobbly, but it opens your hips and helps break your water to facilitate childbirth.

When will relaxin matter? Relaxin levels are highest during the first trimester as your body gears up for pregnancy.

Oxytocin

This isn’t Oxycontin. That’s an opioid pain medication. This is nature’s version.

What does oxytocin do? Oxytocin (pronounced oxy-toh-son) is our favorite hormone. This so-called love hormone floods your brain during sex, childbirth and breastfeeding and gives you the warm and fuzzies.

When will oxytocin matter? This hormone starts your contractions, keeps going through labor and makes your uterus contract after birth. Then every time you nurse, your brain produces more of it to help you bond with your baby. Human bodies for the win!

Prolactin

Pro = for and lactin = milk.

What does prolactin do? As its name suggests, prolactin helps your body produce milk.

When will prolactin matter? When you’re pregnant, prolactin levels go up 10 to 20 times to prep your mammary glands for milk production. The levels stay high if you start breastfeeding. Prolactin levels are highest when you’re sleeping and in the early morning (which may be why many women experience their highest levels of milk production around that time).