Not only are they carrying more kilos, heavily pregnant women also sleep less and snore more.
New research has confirmed what many couples sensed - women in the later stages of pregnancy lose one hour of sleep a night, have poorer-quality sleep and snore more than before they were pregnant.
The study, led by Massey University's Sleep/Wake Research Centre, showed 1091 Kiwi women, aged between 16 and 46 and 35 to 37 weeks pregnant, found their quality of sleep got worse and more uncomfortable as their pregnancies progressed. Frequent visits to the toilet, followed by discomfort and pain and the baby kicking and moving were also the main reasons for broken sleep three or more nights a week.
Almost a quarter of the women surveyed also admitted they started snoring loudly more than three times a week in the late stages of pregnancy.
Co-principal investigator of the E Moe Mama study, Dr Sara-Jane Paine, said the findings around increased snoring were most surprising and worrying because other research had found newly developed snoring could indicate health problems.
Rosie Gibson's sleep hasn't been the same since she became pregnant. At the beginning of her pregnancy, she was woken up by hunger pains so she would have to pour herself large cups of Milo to settle them.
Now at 35 weeks her sleep is broken from the baby moving and leg cramps. The 29-year-old Wellington PhD student thought she had managed to escape snoring until last week, when her boyfriend, Gavin Mouldey, started asking her to turn over because she was breathing heavily in her sleep.
"My sleep is now disturbing my partner and we are just starting to talk about would it make sense if we actually slept in separate rooms because between us we are waking each other up," the first-time mum-to-be said.
She is also surrounding herself with various shaped cushions to help her to sleep.
Sleep Store founder Louise Tanguay said most pregnant women experienced sleepless nights.
The mother of four said the best tips for improving sleep were getting a good, long maternity pillow to keep the pelvis at the right angle and not drinking too much in the evening.
The research will be used to develop guidelines, material and support information for medical practitioners to help sleep-deprived mums-to-be.
A lack of sleep in pregnancy has been found to affect women's health, such as causing longer labours, making more medical intervention necessary during a birth, such as a caesarean section, or causing mood changes once the baby arrives.
Counting the Zzzs
* Pregnant women sleep 1 hour less a night.
* Almost a quarter snore loudly three nights or more a week.
* Sleep was poorer and less comfortable.
* More frequent visits to the toilet during the night.