And one of the biggest surprises for lots of women is how it affects their sex lives.
It's all down to changes to your pelvic health. Pelvic floor disfunction is a general term that covers incontinence, pelvic organ prolapse and sexual problems.
Women can be in such pain and discomfort during sex that they give up on it all together and are often too embarrassed to go to their doctor.
Physiotherapist Sue Brook used to see the problem first hand on almost a daily basis. She worked for the NHS for 11 years and left last month to set up her own clinic in Ripponden. She specialises in women's health issues and says sexual problems after giving birth are a lot more common than people imagine, but it's a very taboo subject.
"Some women feel uncomfortable or heavy, some have a leaky bladder, some lose feeling and others lose their libido. While women are generally better at communicating than men they still find it difficult to talk to anyone about these problems which only makes matters worse."
She says females don't share their concerns with their husbands or friends and often doctors don't have the time to listen to their problems. Which is where she comes in.
"There is a big element of counselling in my work. I'm a bit like a sexual counsellor in that I encourage women to talk frankly. I'm a good listener and once their problems are out in the open I can help them sort it."
She does a full assessment and examination and treatment can include pelvic floor muscle training, exercises and advice, and neuromuscular stimulation. Sue is also at the end of a phone to help them if they are struggling. "My work is very satisfying because women tell me I have helped save their marriages or changed their lives. They feel a lot better about themselves and have a better body image."
Pelivic floor dysfunction can be caused by a traumatic delivery. The number of children a woman has can also play a role as can genes.
Sue, who lives in Kebroyd, Ripponden, also deals with other pelvic floor, bladder and bowel problems and her patients include pregnant women, those who face a hysterectomy or other surgery, and females going through the menopause.
She used to work as a dance teacher at Wellesley Park, Halifax, for 20 years before changing career at the age of 44, and says while there are a lot of physiotherapists about, ones that specialise in women's health are few and far between.
She is based at Back To Fitness Physiotherapy, Mill Fold, Ripponden.