Use of certain herbal supplements, like almonds, during pregnancy can raise the risk of premature birth, says a new study from Italy.

Researchers from University of Modena and Reggio Emilia found that use of almonds during pregnancy was associated with increased risk of babies being born pre-maturely. However, researchers say that only further research on the subject can confirm whether almond oil or any other herbs used during pregnancy can affect the outcome of pregnancy.

The study, published in the journal Human Reproduction, involved 700 Italian women who were interviewed three days after childbirth. Participants were asked about their diet and if they'd taken any herbal supplements during pregnancy.

In the study group, nearly 190 women reported that they used herbal supplements frequently. Almond oil, chamomile and fennel were the most commonly used herbs.

Researchers found that herb use was associated with the baby's birth timing and its weight. Women using almond oil were more likely to give birth to premature babies than women who were using chamomile or fennel. The risk of early delivery remained even after the researchers adjusted other factors like multiple pregnancy, smoking, lifestyle etc., which might have affected the birth outcome.

A related study published in 2010 had found that many pregnant women in the U.S. were using herbal supplements as they believed herbs were natural and so wouldn't harm the baby. In this study, around 6 percent of women had reported that they used herbs.

In the U.S., premature births occur in 8 to 10 percent of all pregnancies, according to MedlinePlus. Premature babies or preemies are born before 37 weeks of the pregnancy. Preterm babies are at higher risk of learning disabilities, cerebral palsy, problems associated with breathing, vision and hearing loss and digestive problems.