Context: Docosahexaenoic acid (DHA) is an important fatty acid required for neurological development but its importance during early fetal neurological organogenesis is unknown.
Objective: This study aimed to assess plasma fatty acid changes in early pregnancy in women undergoing natural cycle-frozen embryo transfer as a means of achieving accurately timed periconceptual sampling.
Design: Women undergoing frozen embryo transfer were recruited and serial fasting blood samples were taken pre-luteinizing hormone (LH) surge, and at 18, 29, and 45 d post-LH surge and fatty acids were analyzed using gas chromatography.
Setting: This study took place at the Assisted Conception Unit, Glasgow Royal Infirmary, Scotland.
Main outcome measures: Plasma fatty acid concentrations and influence of twin pregnancies on DHA plasma concentration were measured.
Results: In pregnant women, there was a rapid, early increase in the maternal rate of change of plasma DHA concentration observed by 29 d post-LH surge (mean ± SD, from 0.1 ± 1.3 to 1.6 ± 2.9 nmol DHA per mL plasma per day). This early pressure to increase plasma DHA concentration was further emphasized in twin pregnancies where the increase in DHA concentration over 45 d was 2-fold higher than in singleton pregnancies (mean ± SD increase, 74 ± 39 nmol/mL vs 36 ± 40 nmol/mL). An index of delta-6 desaturase activity increased 30% and positively correlated with the rate of change of DHA concentration between 18 and 29 d post-LH surge (R2 adjusted = 41%; P = .0002). DHA was the only fatty acid with a continual accelerated increase in plasma concentration and a positive incremental area under the curve (mean ± SD, 632 ± 911 nmol/mL × d) during the first 45 d of gestation.
Conclusions: An increase in maternal plasma DHA concentration is initiated in human pregnancy prior to neural tube closure which occurs at 28 d gestation.