Maternal Plasma DHA Levels Increase Prior to 29 Days Post-LH Surge in Women Undergoing Frozen Embryo Transfer: A Prospective, Observational Study of Human Pregnancy.

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.