Maternal Fatty Acid Desaturase Indices in Early Pregnancy and Risk of Low Birth Weight

Long chain polyunsaturated fatty acids are an important determinant of the birth weight of the baby. Studies have reported altered fatty acid desaturase indices (Δ5 and Δ6 desaturases) from early pregnancy in women with pregnancy complications. However, it remains unclear if these alterations are also observed in women who have no complications, yet delivering low birth weight (LBW) infants (birth weight below 2500 g regardless of gestational age). This study aims to longitudinally examine the maternal erythrocyte fatty acids levels in women delivering LBW babies (in women with pregnancy complications and without complications) and in women delivering normal birth weight babies (NBW). This study includes 1096 singleton pregnant women, out of which 181 delivered LBW babies. Maternal erythrocyte fatty acids were measured at 11-14 weeks, 18-22 weeks, and 26-28 weeks and at delivery using gas chromatography. Product-precursor ratios were used to represent enzyme indices: Δ5D index = arachidonic acid/dihomo-y-linolenic acid (DGLA), Δ6D index = DGLA/linoleic acid. Maternal age at the time of delivery was: NBW group: 28.74 ± 4.65; LBW group: 28.14 ± 4.61 and LBW without complications group: 26.99 ± 4.20. Birth weight of the baby was: NBW: 2978.69 ± 340.37; LBW: 2404.47 ± 262.85; LBW without complications group: 2308.02 ± 202.06. Higher Δ5 desaturase and lower Δ6 desaturase indices at 11-14 weeks of gestation were associated with higher risk of having LBW babies (p < 0.01 for both). This study reports that disrupted fatty acid metabolism in early pregnancy regardless of pregnancy complications is a risk factor for having LBW babies.