In the study, women who reported nausea and vomiting in pregnancy that interfered with their ability to live normally were 23 per cent more likely to deliver their baby before 34 weeks, and 31 per cent more likely to have high blood pressure or preeclampsia, compared with women who said their morning sickness did not substantially affect their lives.
Women with life-affecting morning sickness were also about twice as likely to have low weight gain during pregnancy, website MyHealthNewsDaily reported.
The findings underscore the importance of recognising morning sickness and managing it, said study researcher Dr Gary Stanziano, of Alere Health, a company that produces health care products and offers a programme to treat morning sickness.
"This should not be a condition that's taken lightly," Stanziano said.
About 50 to 60 per cent of pregnant women experience some type of morning sickness during pregnancy, Stanziano said. About 1 per cent have a severe, persistent form known as hyperemesis gravidarum, which can lead to malnutrition.
While the immediate effects on mothers are easy to observe, few studies have investigated the impact of nausea and vomiting on the later stages of pregnancy, and delivery.
Stanziano and colleagues analysed information from 81,486 women enrolled in an Alere maternity education programme who delivered between 2004 and 2011.
After delivery, the women were asked whether they had experienced nausea and vomiting during their pregnancy that affected their ability to do their job or their daily activities.
About 5,200 women, or 6.4 per cent of those surveyed, reported nausea and vomiting that affected their quality of life. About 1,800 women of these said they did not require any interventions, while about 3,300 required hydration or pharmacological treatments.
Of those who said the nausea and vomiting affected their quality of life, 23 per cent had low weight gain for their pregnancy, compared with 13.7 per cent of women who did not have such sickness.
In addition, about 10 per cent of those who got sick had infants who were small for their gestational age when they were born, compared with 8.4 per cent of those who didn't have nausea and vomiting.
Researchers are not sure why women with severe morning sickness saw these effects. But poor nutrition and too little weight gain in pregnancy may contribute to the risk, Stanziano said.
