A randomized longitudinal dietary intervention study during pregnancy: effects on fish intake, phospholipids, and body composition.

Background: Fish and meat intake may affect gestational weight gain, body composition and serum fatty acids. We aimed to determine whether a longitudinal dietary intervention during pregnancy could increase fish intake, affect serum phospholipid fatty acids, gestational weight gain and body composition changes during pregnancy in women of normal weight participating in the Pregnancy Obesity Nutrition and Child Health study. A second aim was to study possible effects in early pregnancy of fish intake and meat intake, respectively, on serum phospholipid fatty acids, gestational weight gain, and body composition changes during pregnancy.

Methods: In this prospective, randomized controlled study, women were allocated to a control group or to a dietary counseling group that focused on increasing fish intake. Fat mass and fat-free mass were measured by air-displacement plethysmography. Reported intake of fish and meat was collected from a baseline population and from a subgroup of women who participated in each trimester of their pregnancies. Serum levels of phospholipid arachidonic acid (s-ARA), eicosapentaenoic acid (s-EPA), and docosahexaenoic acid (s-DHA) were measured during each trimester.

Results: Weekly fish intake increased only in the intervention group (n = 18) from the first to the second trimester (median difference 113 g, p = 0.03) and from the first to the third trimester (median difference 75 g, p = 0.01). In the first trimester, fish intake correlated with s-EPA (r = 0.36, p = 0.002, n = 69) and s-DHA (r = 0.34, p = 0.005, n = 69), and meat intake correlated with s-ARA (r = 0.28, p = 0.02, n = 69). Fat-free mass gain correlated with reported meat intake in the first trimester (r = 0.39, p = 0.01, n = 45).

Conclusions: Dietary counseling throughout pregnancy could help women increase their fish intake. Intake of meat in early pregnancy may increase the gain in fat-free mass during pregnancy.