Understanding Pregnancy Hormones by Trimester

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Hormones can sneak up on you and throw you for a loop, but if you know what’s coming, you’ll be far more ready when the change comes. Read on to start understanding hormones by trimester.

Table of Contents

First Trimester

Human chorionic gonadotropin (HCG)—otherwise known as the “pregnancy hormone”—is produced after ovulation and peaks toward the end of your first trimester. This is the hormone that pregnancy tests look for, as it is released in urine. HCG tells your body to stop producing eggs once you’re pregnant and may be the cause of morning sickness (though the exact source is still unknown by doctors).

A cyst on the ovary known as the corpus luteum produces progesterone and will continue to do so for the first 10 weeks of your pregnancy. It causes lowered blood pressure, heartburn, nausea, and occasional dizziness, and it can also lead to increased hair growth.

Second Trimester

The second trimester is your opportunity to relax and get comfortable (for a little while) as nausea symptoms abate. Muscles and joints around your pelvis may start to feel odd due to the hormone relaxin, which promotes the growth of the placenta while relaxing the smooth muscles in your pelvis. This discomfort could persist until you give birth, so be ready.

Progesterone continues to help with your baby’s growth, aided by estrogen. This combination comes with the interesting side effect of melanin production, which colors your skin and may cause grey or brown patches around your face. Your nipples may also darken, as well as moles and freckles.

Third Trimester

Prolactin significantly increases in the final trimester, which causes breast tissue development in preparation for lactation. Your breasts may leak before you give birth, so don’t be alarmed if this happens.

Progesterone and estrogen continue their work in the third trimester, leading to swelling in your ankles and feet, as well as acid reflux and heartburn.

Knowledge is one of the most significant keys to a healthy pregnancy, so do all the research you can. There’s more than just understanding pregnancy hormones by trimester, so keep researching. Congratulations on your pregnancy, and good luck with your labor!