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?
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.”
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.