But while a baby is growing inside a mum-to-be, there are so many other changes going on in her body that people may not realise.
Did you know that while a woman’s womb is growing, her internal organs are constantly shifting and moving to accommodate the expanding baby?
We spoke to Lesley Gilchrist, midwife and founder of My Expert Midwife, and Asma Khalil, consultant obstetrician and foetal medicine specialist at The Portland Hospital, part of HCA Healthcare UK, to find out what other changes are happening in a mum-to-be’s body.
Many of the changes that happen to a woman’s body are down to a shift in hormone levels, Dr Khalil explained.
“Specifically, an increase in the amount of progesterone and oestrogen causes what we call ‘normal changes’, as they are not caused by a problem with the pregnancy,” she said.
So what is going on?
1. The womb needs a lot more space.
As a woman’s womb grows, her internal organs are moved.
Dr Khalil explained when you’re not pregnant, the uterus is a very small organ, around the size of your own clenched hand.
But in the first four to 12 weeks, the uterus will grow to the size of a grapefruit.
“At this stage, the change isn’t very noticeable,” she said.
“In the second trimester, the uterus will start to push other organs out of place, as it grows to the size of a papaya, sitting halfway between the stomach and breasts.
“In the third and final trimester, the uterus will grow to the size of a watermelon. As the baby approaches full term, the uterus will extend from the pubic area to the ribcage and the lower ribs will flare out to make space.”
2. Ligaments and tendons relax.
Many hormones are needed for a healthy pregnancy, the main ones being progesterone, oestrogen and relaxin.
“Relaxin’s role is to prevent the uterus contracting, but it also relaxes ligaments and tendons in the body,” explained Gilchrist.
“This means that your muscles need to work harder to compensate for this, leaving you with pelvic pain and back pain.”
Dr Khalil explained that the relaxed ligaments combined with the growth of the womb, which means the ligaments attached to the pelvic bones will be stretched, can also result in painful pelvic joints.
She said some women may also develop an unusual gait as their spine curves towards the end of their pregnancy and they may “walk a bit like penguins”.
“This is due to having relaxed ligaments and tendons, but also due to carrying the weight of the baby,” she explained.
“The weight is at the front so the woman tends to lean backwards without realising it; alsot later in pregnancy the baby’s head is pushing into the woman’s pelvis, which makes it harder to walk.”
3. There are lots of skin changes all over the body.
“It stands to reason that as your womb grows, so does the skin around it,” said Gilchrist. “It’s the speed at which this stretching occurs that causes problems; tightness, itching, nerve pain, stretch marks.
“Some creams, oil or serums will both moisturise and reduce the itching and tightness.”
Gilchrist recommended a ‘Skin Elastic’ cream that has argan oil, geranium oil and lavender oil in.
She added: “Calendula oil also helps to soothe and heal the skin, it’s also great at reducing inflammation and scarring, as is argan oil.”
Khalil said pigmentation will also often occur, known as ‘chloasma’. This can cause areas of a woman’s face to darken and a vertical line known as the ‘linea nigra’ might appear down the centre of the belly.
“Redness can also appear in different areas of the body,” she explained. “Marks called ‘spider naevi’ can emerge where the blood vessels close to the skin dilate, and the hands can redden – this is called ‘palmar erythema’.
“With higher levels of oestrogen in their body, and the increased blood flow to the skin, women sometimes find that their skin quality improves, although women respond differently to hormonal changes, and others might experience dry skin or acne for the first time in years instead.”
4. Increased volume of bodily fluids.
Women gain weight during pregnancy (around 15kg), but Khalil said only a third of this is fat (4-5 kg) and a proportion of it is due to an increase of blood and bodily fluids.
“The volume of blood in the body increases by around two litres (2kg),” she explained. “The breasts grow by around 0.5-1kg, and other bodily fluids make up another 1.5-2kg.
“The baby itself, the placenta and the amniotic fluid weigh approximately 5-6kg themselves.
“The swelling of a woman’s feet during pregnancy is caused by the increased blood volume in the body. When standing, in addition to the increased pressure of the baby, gravity brings extra fluid to the legs and feet.”
5. A lack of bladder control.
From the early stages of pregnancy, women often find they need to go to the toilet more frequently. Khalil explained this is because the increase in blood makes the kidneys work more.
“Towards the end of the pregnancy, as the baby’s head is getting bigger, women often lose control of their urine, particularly when laughing or coughing,” she added.
“I find a lot of my patients are very self-conscious about this. I often have to reassure them that this is very common during pregnancy and it will get better once they have given birth.”
HuffPost UK Parents is running a week-long focus on ‘Mumbod’ to empower mums and mums-to-be to feel confident about their bodies pre- and post-baby. We are launching a section on the site that focuses on all aspects of mums’ bodies and highlights the amazing things they are capable of. We’d also love to hear your stories. To blog for Mumbod, email email@example.com. To keep up to date with features, blogs and videos on the topic, follow the hashtag #MyMumbod.