Pregnancy hormones: hCG, oestrogen, progesterone and your changing body
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From morning sickness to tiredness, indigestion to skin breakouts, a lot happens to your body when you're pregnant. With so many early pregnancy symptoms blamed on hormones, we look into some of the key culprits – hCG, oestrogen and progesterone – to see how they'll affect you in the next nine months.
Even before you see that BFP on the pregnancy test, your pregnancy hormones have already starting doing their stuff.
From the minute you conceive, levels of various hormones such as oestrogen, progesterone and the mother of pregnancy hormones, hCG, start being produced, often by the bucketload.
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The six key hormones to know about are:
- Human Chorionic Gonadotropin (hCG)
- Oestrogen
- Progesterone
- Oxytocin
- Relaxin
- Prolactin
But while these hormones play a vital part in a healthy pregnancy, helping your body adapt and prepare for giving birth and feeding your new baby, they can also take their toll on everything from your skin to your mood.
Yep, all those early pregnancy symptoms are caused by pregnancy hormones. And that indigestion, heartburn, spotty skin and hair loss in later trimesters – yes, you guessed it ... also caused by hormones.
So whether you're curious to know what they do or how they could impact your pregnancy, keep reading to get a better understanding of how hormones work ...
1. What's hCG?
Your body starts producing human chorionic gonadotrophin (hCG) as soon as you're pregnant.
You may have heard of it because it's what home pregnancy tests can detect when you first pee on that stick. If you have sufficient levels of hCG in your urine, you'll get that BFP.
While everyone's hCG levels will differ slightly from each other, they will rise quickly in your first trimester, roughly doubling every 48 hours.
Produced by the chorion (the outer membrane of the amniotic sac) and the placenta, hCG is crucial to having a healthy pregnancy.
Recognising that you're pregnant really early on, it starts putting things in place to help with that. It also tells your ovaries to stop producing eggs and influences steroid production.
Although the exact cause of morning sickness isn't known, many health experts think it could be linked to this particular hormone.
2. What's oestrogen?
Another key pregnancy hormone, oestrogen is what helps your uterus grow and become a safe environment for your baby. It also plays an important part in kickstarting your baby's growth and development.
As your levels of oestrogen rise in the first trimester, it's also the reason you may (although not always) experience some of these not so pleasant early pregnancy symptoms:
- sore or tender boobs
- blocked nose
- headaches
- changes to your skin (sensitivity, spots, discolouration, melasma)
- increased appetite
- nausea
On the positive side, if people comment on your pregnancy 'glow', this is most likely down to oestrogen.
3. What's progesterone?
Produced by your ovaries in the early weeks of pregnancy, progesterone helps the body prepare for and tolerate your pregnancy.
Towards the second trimester, your placenta will produce this hormone keeping it – as well as your uterus lining – nice and healthy as the baby grows.
Although this keeps your baby comfortable, it can impact your internal organs by causing more of those unpleasant early pregnant symptoms such as:
- heartburn
- indigestion
- constipation
- reflux
- bloating
- gas
Progesterone also helps to relax blood vessels, which can cause low blood pressure and therefore dizziness or lightheadedness – pretty common in pregnancy.
Progesterone is also the hormone behind hair growth – as well as helping your hair look glossier and thicker than ever it can also cause unwanted hairs sprouting up, too.
4. What's oxytocin?
In the early stages of labour – known as the latent phase – the body produces oxytocin, a hormone that stimulates contractions during labour.
The more relaxed you are at this stage, the more you'll produce, helping labour progress.
Oxytocin is also associated with being induced.
That's because if you go overdue or things don't progress, you'll need to be have some help kickstarting things.
Part of the induction process will require a Syntocinon drip.
This drug mimics oxytocin, helping to start things artificially.
Once your baby's born you might choose to have a Syntometrine injection (containing oxytocin) to help deliver the placenta.
Breastfeeding also helps produce oxytocin to help your uterus contract and shrink back to its original size.
The oxytocin also helps your glands squeeze out milk when your baby is ready to feed. It's what causes the 'letdown' reflex – that slightly uncomfortable feeling you get as your milk comes in.
5. What's relaxin?
As its name suggests, relaxin helps things to relax during your pregnancy and labour.
As your baby grows inside you, relaxin helps things stretch and flex, to create room for it.
While this is great news for your baby who'll be nice and comfortable as a result, it can create problems for mums-to-be.
For instance, it can make you more prone to back pain, joint pain and general aches and pains as your ligaments loosen.
That's why it's important not to overstretch or push yourself during exercise as it's easier to injure yourself or damage ligaments.
Relaxin is also key in helping push your baby out at the end of your pregnancy, loosening the muscles of your uterus and enabling the pelvis to stretch during labour.
6. What's prolactin?
Prolactin is a milk-producing hormone.
It starts to be produced by your pituitary gland during your first trimester and gets the body ready for breastfeeding.
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