M STRØM1, E MASLOVA1, S HANSEN1,
EL MORTENSEN2 & SF OLSEN1,3
1Centre for Fetal Programming, Department of
Epidemiology Research, Statens Serum Institut,
Copenhagen, Denmark, 2Institute of Public Health and
Center for Healthy Aging, University of Copenhagen,
Copenhagen, Denmark, and 3Department of Nutrition,
Harvard School of Public Health, Boston, USA
Background: Fish oil contains docosahexaenoic acid
(DHA), the most abundant fatty acid in the cerebral cortex.
Previous studies have suggested beneficial effects of
maternal DHA intake on brain development and psychopathology
in the offspring.
Objective: To examine the effect of fish oil supplementation
in pregnancy on offspring risk of attention deficit/
hyperactivity disorder (ADHD) and depression.
Methods: We used data from 397 and 654 singleton offspring
of mothers who were randomized to fish oil (providing
1 g/day of DHA) or olive oil during pregnancy as
participants in: the RCT90, a single center trial enrolling
normal pregnancies in 1990, and FOTIP, a multicenter
trial enrolling high-risk pregnancies during 1990–1996.
We used definitions of ADHD and depression based
on ICD-10 codes and drug dispensary data, using information
on first prescription/hospital contact as a proxy
for ADHD and depression, respectively. We performed
intention-to-treat analysis and report odds ratios (ORs)
and 95% CI comparing the two intervention groups.
Results: There were 17 and 35 cases of ADHD among offspring
to participants in RCT90 and FOTIP, respectively;
for depression corresponding numbers were 46 and 31. In
both trials there was a reduced risk of ADHD in the fish
oil groups, but this was not statistically significant
[OR = 0.73(95% CI: 0.27;1.97), OR = 0.75(95% CI:
0.38;1.50), respectively]. For depression, in the RCT90
there was a non-significant reduced risk in the fish oil
group, [OR = 0.71(95% CI: 0.38;1.33)]; whereas the OR
in the FOTIP was approaching unity [OR = 1.09 (95%CI
0.53;2.25)].
Conclusions: We found no statistically significant effects
of fish oil supplementation during pregnancy on ADHD
or depression in the offspring up to the age of 14–20.
However, the results regarding ADHD point in the direction
of a beneficial effect. The next step will be to pool
the two trials in a random effects model to test this in a
population with better statistical power.