It’s a well-documented phenomena that pregnancy has a tendency to make perfectly normal, level-headed women turn into achy, tired, crazed creatures from time-to-time. There’s no shame in feeling like you’re about to rip someone’s head off or pass out for an eight-hour nap—you’re not to blame, after all! So what exactly is responsible for these often drastic changes in body and temperament? Hormones! Here are six you ought to get to know.
1. Human chorionic gonadotropin (hCG)
This is the hormone that helps doctors (and at-home pregnancy test-takers) determine a pregnancy. It stimulates the corpus luteum (the part of the egg follicle left in the ovary after ovulation) to produce the hormones estrogen and progesterone in the first 10 weeks of pregnancy until the placenta can take over the job for the duration. It’s also responsible for increasing blood flow to your pelvic region, which can make your bladder feel extra sensitive. Blame hCG for those frequent trips to the bathroom during the first trimester.
2. Progesterone
This hormone prepares your uterus for implantation, calming the muscle so the fertilized egg can successfully attach and begin to grow. Levels increase throughout pregnancy to maintain the inner layer of the uterus that supports the fetus. Progesterone also promotes sleep, which is one of the main reasons why it’s been shown to help women deal with stress during a pregnancy. While it’s certainly helpful, this hormone can sometimes be responsible for acne breakouts and night sweats – it raises your temperature so your baby stays warm and comfortable in the womb.
3. Estrogen
This group of three hormones stimulates uterus growth and improves the blood flow between the uterus and the placenta. It also prepares your breasts for milk production by widening the milk ducts. Believe it or not, estrogen levels are 100 times higher during a pregnancy than during a period, and levels peak right before birth and decline afterward. Estrogen levels are often to blame for decreased sex drives, positive and negative mood changes and headaches. It can also increase cervical and vaginal mucus production, meaning you may notice more discharge than normal.
4. Relaxin
This hormone loosens the joints and ligaments in your pelvis to prepare for delivery, and it widens your blood vessels to compensate for the increased blood flow. Sounds helpful, but it often affects other parts of the body too, which is why it’s to blame for a variety of common pregnancy ailments. For example, it relaxes the muscle that prevents stomach acid from coming up into the esophagus, which is why heartburn often occurs after meals or at night. It can also make your feet wider, your back hurt and your former grace disappear. (Many pregnant women report feeling clumsy or more prone to falls.)
5. Prolactin
Also known as the milk-producing hormone, prolactin develops your breast glands and changes the structure of breast tissue to prepare your body for breastfeeding your baby. It’s usually the main reason why your breasts feel tender and sensitive during and immediately following a pregnancy.
6. Oxytocin
Often referred to as the bonding hormone, oxytocin helps us develop bonds with others – specifically your baby when you’re pregnant. That’s why pregnant women often experience extreme happiness and nesting behavior when they’re preparing for delivery. During labor, the hormone helps relieve pain and causes the uterus to contract. It also allows your breasts to produce milk when you breastfeed. This one’s probably the nicest!