All About Pregnancy Hormones

All through your life, your health and well-being depend on hormones, the chemical messengers that coordinate and control the functions of cells and organs. When you're pregnant, hormones play an especially prominent role, helping to protect and nourish your baby and prepare your body for childbirth and motherhood. During each trimester of pregnancy, you'll go through a roller-coaster ride of physical and emotional changes thanks to the rise and fall of various hormones.

How will these shifting hormonal levels affect your body and your emotions? Check out this guide to the most important hormones in pregnancy, which will take you through what they do, and how they might make you feel.

HormoneWhen Most ActiveFunctionRelated Symptoms
Hormone (LH)
OvulationRegulates estrogen 
Hormone (FSH)
OvulationStimulates ovulation 
Human Chorionic
First trimester of
Triggers increase in
production of estrogen
and progesterone
Pregnancy glow
Morning sickness
EstrogenThroughout adult
life; increases in
first trimester
Fuels the growth of the
Morning sickness
Mood swings
ProgesteroneThroughout adult
life; increases in
first trimester
Helps build the lining of
the uterus; increases
blood supply to the
breasts and pelvic area
Digestive issues
Pregnancy glow
Mood swings
RelaxinThird trimesterRelaxes and prepares
ligaments for labour
Loose joints and
Pain in pelvic area
Dilation during
OxytocinThird trimester
and after
Helps promote bonding
between you and your
baby; stimulates milk flow
during breastfeeding.
Synthetic forms can be
used to induce labour.
Creates feelings of
love and trust
Euphoric state after
ProlactinThird trimester
and after
Triggers breast milk
Engorged breasts
Euphoric state after


Hormones Play an Important Role in Getting Pregnant

When it comes to your fertility, there are two crucial hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH regulates the estrogen levels in your body and works with FSH to stimulate the development and release of egg cells.

HCG Has “You’re Pregnant” Written All Over It

Shortly after a fertilized egg attaches itself to the lining of your uterus, and the placenta begins to form, your body begins to produce the hormone called human chorionic gonadotropin (hCG). This is one of the main pregnancy hormones your body will produce in the first trimester, and the amount of hCG will double every couple of days in those early weeks. HCG alerts your ovaries to stop releasing eggs and also signals the body to produce more estrogen and progesterone. Because this hormone is unique to pregnant women, and also because it enters your bloodstream and urine, home pregnancy tests are designed to detect it. Bear in mind, if you’re in the very early stages of pregnancy, the amount of hCG in your body may be still too little for a positive test result, so consider taking another pregnancy hormone test a week later if you still think you may be pregnant. Then, if you’re wondering how far along you are you can get an estimate by using the Pampers due date calculator.

In addition to the increased blood flow that gives you a flushed look, hCG is responsible for that special “pregnancy glow.” The increased production of this hormone, along with progesterone, help make the glands in your skin secrete more oil, giving you that shimmer.

Along with that glow, doctors believe hCG is one of the hormones that may cause morning sickness.

Some Pregnancy Hormones Are Not Unique to Pregnancy

The main hormones your body produces during pregnancy, estrogen and progesterone, have been active since puberty. Working together, these hormones regulate your monthly cycle and the development of those characteristics that make you female. In early pregnancy, the levels of these hormones increase week by week, and this increase stops your period and fuels the growth of the placenta. Estrogen and progesterone also help to build up the lining of your uterus, increase blood supply to the pelvic area and breasts, and relax your uterine muscles. These are also the pregnancy hormones behind those intense emotions and mood swings you’re likely to go through during pregnancy. Once your baby is born, the levels of these hormones will fall, which in turn can contribute to postpartum depression for some women.

Furthermore, when it comes to fatigue and digestive issues, you may have progesterone to blame. During the early days of your pregnancy, your progesterone levels will increase, making you feel tired. At the same time, this increase in progesterone also slows the movement of food through the digestive system, which can cause gas or constipation.

Relaxin Prepares Your Body for Childbirth

During the late stages of pregnancy, a hormone called relaxin prepares your body for labour. It helps relax the ligaments and other joints in the pelvic area, so your pelvis can expand during delivery. Relaxin also softens the cervix.

Oxytocin Helps You Bond With Your Baby

Nicknamed “the love and trust hormone,” oxytocin plays a role in helping to form that special bond between mothers and their children. So, as you're falling in love with your baby, you have this hormone to thank.

Although the synthetic form of oxytocin can be used to help induce labour, there is no evidence that the natural oxytocin produced by your body contributes to the labour process itself. After pregnancy, oxytocin is one of the hormones that help stimulate milk flow during breastfeeding.

Prolactin Gets the Milk Flowing

Prolactin is responsible for triggering the production of breast milk, and your body makes this hormone during and after pregnancy. This hormone will initiate and increase milk production, but the act of breastfeeding and expressing milk triggers the body to create more of this hormone, which, in turn, stimulates the breasts to produce more milk.

Over the course of your pregnancy, you'll likely experience many changes that are brought about by hormones. Take some time to learn about all the interesting and wonderful things pregnancy hormones are helping your body achieve, and talk about these with your partner, too, who can be there to help support you, each step of the way.