Blubbing at TV ads one minute, struggling to keep your lunch down the next? Yep… that’ll be those pesky pregnancy hormones.
Medically reviewed by Dr Juliet McGrattan (MBChB) and Words by Pradnya Pisal
Pregnant and feeling a little peculiar? After the excitement of seeing those parallel blue lines appear on the little white pregnancy test stick you peed on, it can be a bit of a shock when rampaging chemicals (AKA pregnancy hormones) start to play havoc with everything from your mood, to your skin, to your digestion.
Want to know what to really expect when you’re expecting, courtesy of your hormones? Pradnya Pisal, consultant gynaecologist and obstetrician at London Gynaecology gives us the lowdown on the emotional and physiological changes you might experience, thanks to the six key pregnancy hormones:
Human chorionic gonadotropin (HCG)
HCG appears on the eighth day after ovulation, and is one of the earliest secreted hormones. It can usually be detected five to six days after ovulation, but definitely by 10 days after.
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- HCG peaks
HCG hormone doubles every 48 hours in early pregnancy, hitting its maximum level at around eight to ten weeks.
- HCG function
HCG supports the corpus luteum (essential for conception to occur and the pregnancy to last). Its rising levels trigger the body to start preparing for pregnancy and it regulates the production of oestrogen and progesterone.
- HCG side-effects
Headaches, irritability, restlessness, fatigue, insomnia, nausea and vomiting (the dreaded ‘morning sickness’) and frequent urination.
Oestrogen is produced from pre-pregnancy until about 10 to 12 weeks from the follicle area in the ovary (corpus luteum), where the egg is released from. The placenta and fetal adrenal gland then produce it until term.
- Oestrogen peaks
Oestrogen hormone tends to peak in the late third trimester.
- Oestrogen function
Oestrogen prepares the uterine lining for implantation of the embryo. It helps the growth and function of the placenta. It is also helpful in preventing miscarriage and is a catalyst for chemical changes for growth, development and energy in the baby. Oestrogen steps up blood circulation, regulates the production of other key hormones and promotes breast engorgement in preparation for breast feeding.
- Oestrogen side-effects
Oestrogen side-effects include mood swings and nausea (along with other rising hormone levels). Increased blood flow to mucous membranes can cause headaches, postnasal drip and nasal congestion (along with progesterone). Some areas of your skin my also experience hyperpigmentation, especially the areola and along the midline on the abdominal wall.
Progesterone is produced from pre-pregnancy until about 10 to 12 weeks from the follicle area in the ovary (corpus luteum), where the egg is released from. The placenta then produces it until term.
- Progesterone peaks
Progesterone hormone usually peaks in the late third trimester.
- Progesterone function
Progesterone works closely with oestrogen. Increases blood flow to the uterus to prepare it for pregnancy. Thickens the uterine lining for implantation of the embryo and nourishing the embryo until the placenta is formed and able to take over. It suppresses the mother’s response to foetal antigens, helping to prevent the mother’s body rejecting the embryo, which can result in miscarriage or premature labour. Progesterone helps the development of the foetus and also strengthens the pelvic muscles in preparation for labour.
- Progesterone side-effects
Gastrointestinal discomfort, including indigestion, heartburn, constipation and bloating; aching hips, pubic bone and back; bleeding gums; and increased sweating.
Relaxin is produced by the corpus luteum and the placenta from early through to late pregnancy.
- Relaxin peaks
Relaxin hormone peaks at 14 weeks and then again around the time of delivery.
- Relaxin function
Relaxin helps to prepare the uterine lining for implantation of the embryo, assists uterine growth to accommodate your growing baby, helps to prevent premature labour, assists cervical ripening, important to facilitate labour, relaxes pelvic ligaments in preparation for birth and reduces insulin resistance. It also helps the circulation of the mother increase to meet the demands of a growing baby by relying blood vessel walls.
- Relaxin side-effects
Due to the fact it relaxes ligaments, relaxin can cause joint and ligament pain, and backache. It can also cause heartburn, as it relaxes the smooth muscle and sphincter of the stomach, enabling acid to flow back up into the food pipe.
Oxytocin is produced by the hypothalamus and is released from the pituitary gland in the mother’s brain throughout pregnancy.
- Oxytocin peaks
Oxytocin levels rise from the first to the third trimester, and fall during the postpartum period, after birth.
- Oxytocin function
Oxytocin stimulates the ripening of the cervix, which allows it to dilate during labour. Along with other hormones, it causes the release of prostaglandins, which may also help to ripen the cervix. It helps to trigger and maintain contractions of the uterus during delivery and continues to contract the uterus after delivery of the baby to reduce bleeding and allow the placenta to be shed. Sometimes referred to as the ‘love’ hormone, this is also the chemical that helps you bond with your newborn and release milk when the baby suckles, if you are breast feeding.
- Oxytocin side-effects
Oxytocin can cause irritability and Braxton-Hicks which are painless contractions of the uterus.
Prolactin starts to be secreted in early pregnancy.
- Prolactin peaks
There is a sustained rise in prolactin throughout pregnancy, which continues after birth.
- Prolactin function
Prolactin is responsible for the enlargement of the mammary glands and milk production, which normally starts when levels of progesterone fall at the end of pregnancy, and a suckling stimulus (your baby!) is present.
- Prolactin side-effects
Prolactin side-effects include irregular periods or cessation of menstrual periods.