The onset of “morning sickness”, the nausea and vomiting that often occurs near the beginning of pregnancy and normally resolves at 12-14 weeks, has been narrowed down in a new study from researchers at the University of Warwick.
The cause of nausea and vomiting of pregnancy (NVP) had historically been ascribed to psychological conditions, but currently is believed to have a multifactorial basis, involving various genetic, endocrine and gastrointestinal factors.
The study involved 256 women who became pregnant, keeping a diary recording the onset of nausea and vomiting, their last menstruation and date of ovulation as measured by a urine test.Determining the date of the start of pregnancy as determined by the date of their last ovulation, the first onset of NVP was 8 to 10 days, compared to 20 to 30 days as measured from the date of their last menstruation.
Lead author Prof Roger Gadsby, Warwick Medical School, said: “The precise course of pregnancy sickness is unknown, but this research shows that it occurs at a specific developmental stage, in a specific timeslot. For researchers it narrows our focus in terms of where we look for the cause. If we know that symptoms occur in a very narrow window 8-10 days after ovulation, researchers can concentrate their efforts on that particular stage of development to find the cause of the condition, both anatomically and biochemically.”
Knowing that the onset of NVP has such a tight timeframe will help future research narrow down a biological cause behind it, and help generate targets for treatment development.
An unexpected outcome of the study was a very high prevalence of NVP of 94%, compared to the 80% calculated in prior research. This is explained by the fact that data were regularly collected from participants from before they became pregnant to 60 days after their last menstruation, as opposed to most studies asking women to recall symptoms after they became pregnant.
Prof Gadsby added, “What we’ve shown is that more people get symptoms of pregnancy sickness than has ever been shown before, and one of the reasons for that is that this research has picked up mild early symptoms that tend to fade by 7-8 weeks. In other studies those symptoms would have faded by the time the research started.”
Source: News-Medical.Net
