In the study, which was conducted by researchers from the University of Gothenburg, Sahlgrenska University Hospital and the Norwegian Institute of Public Health, the participants completed a scientifically evaluated questionnaire about what they had been eating and drinking since becoming pregnant.
The researchers also had access to information about the women's general lifestyle e.g. level of education, living conditions, income, weight, physical activity, smoking habits, alcohol consumption, number of children and medical factors such as history of preterm delivery.
15 % lower risk
The results show that the group of women with the 'healthiest' pregnancy diet had a roughly 15 % lower risk of preterm delivery compared with those with the most unhealthy diet. The correlation remained after controlling for ten other known risk factors for preterm delivery.
'Pregnant women have many reasons to choose a healthy diet with lots of vegetables, fruit, whole grain products and some types of fish, but this is the first time we can statistically link healthy eating habits to reduced risk of preterm delivery,' says Linda Englund-ögge, researcher at the Sahlgrenska Academy, University of Gothenburg.
Associated with complications
Preterm delivery, defined as spontaneous or induced delivery before the end of gestational week 37, can be associated with acute and long-term complications and is a major problem in modern maternity care. Measures to prevent preterm delivery are therefore of high priority.
Should this lead to revised dietary recommendations for pregnant women?
'No, and it is not harmful to occasionally eat something unhealthy. But our study shows that the dietary recommendations given to pregnant women are important,' says Englund-ögge:
'Dietary studies can be very complex. Any given food item may contain a wide range of substances and is usually consumed together with other foods. This makes it difficult to find out its exact effects of one single food. We show that there is a statistically established link between a healthy diet and reduced risk of preterm delivery, but our study wasn't designed to identify any underlying mechanisms.
Encourage healthy eating habits
Englund-ögge says that studies of the overall dietary pattern and the total quality of the foods consumed are important complements to coming studies of how single food items affect the risk of preterm delivery. The researchers are hoping that the study will inspire doctors, midwives and others who work with pregnant women to encourage healthy eating habits.