Researchers say they have identified a number of lifestyle factors that could be modified in order for a woman to have a healthy pregnancy. This is according to a study published in the BMJ.

According to the Centers for Disease Control and Prevention (CDC), there are around 6 million pregnancies in the US every year.

Many of these women may experience complications during pregnancy, which can range from anemia and urinary tract infections (UTIs), to more serious conditions, such as preeclampsia and preterm birth.

But a collaboration of investigators from the UK, Ireland and New Zealand say that by changing certain lifestyle factors, such as increasing fruit intake before pregnancy and maintaining a healthy weight, pregnant women may "increase their likelihood of normal pregnancy outcomes."

To reach their findings, the investigators analyzed 5,628 healthy women with singleton births who had no previous pregnancies. Of these, 3,196 were from Australia and 2,432 were from the UK and Ireland.

The researchers analyzed the women from 15-20 weeks' gestation in order to identify factors throughout their pregnancies that may be linked to reduced risk of complications.

Of all women, 61% (3,452) had an uncomplicated pregnancy. The researchers defined this as "normotensive pregnancy, delivered at more than 37 weeks resulting in a live born baby who was not small for gestational age and did not have any other significant pregnancy complications."

Women in the UK and Ireland had the lowest proportion of uncomplicated pregnancies at 58%, compared with 63% in Australia.

The most common reasons for complicated pregnancies in women were babies being small for gestational age (11%), followed by gestational hypertension (8%), preeclampsia (5%) and spontaneous preterm birth (4%).

'Reduced complications' with paid employment and fruit

The investigators found the factors that appeared detrimental to women and caused them to experience pregnancy complications were increasing body mass index (BMI), high blood pressure and misuse of drugs (including binge drinking) within the first trimester.

However, the likelihood of pregnancy complications appeared to reduce for women who had high fruit intake the month before becoming pregnant and who were in paid employment 15 weeks into pregnancy.

The researchers add that they did identify risk factors for pregnancy complications that could not be altered. These were high blood pressure prior to pregnancy as a result of contraceptive pills, family history of high blood pressure during pregnancy, and bleeding during pregnancy.

Commenting on their findings, the researchers say:

"Based on a large prospective cohort study of healthy nulliparous women, we identified, replicated, and externally confirmed improvable factors associated with uncomplicated pregnancy.

These related to optimizing weight, diet, cardiovascular fitness, and cessation of illicit drug use. Providing confirmation is forthcoming from other cohorts, this study should inform development of interventions to increase normal pregnancy outcomes."

Interventions to reduce blood pressure 'could be effective'

Lifestyle recommendations already exist for people who are non-hypertensive to maintain a healthy blood pressure, the researchers say. These include carrying out regular physical exercise, weight reduction, reducing salt intake and alcohol consumption and following a healthy diet.

The researchers note that their study suggests adoption of these choices "seems to be beneficial in determining subsequent uncomplicated pregnancy."

They emphasize this point by adding that a 5 mm Hg reduction of maternal systolic pressure would reduce the occurrence of uncomplicated pregnancies by 3% in the UK, equating to 24,674 more women having healthy pregnancies.

But they note further trials are warranted to back this up, and if their study findings are confirmed, they "should inform development of interventions to increase normal pregnancy outcomes."

Medical News Today recently reported on a study suggesting that maternal exercise could benefit newborn brain development.