Parity and the use of folic acid supplementation during pregnancy

Folic acid (FA) supplementation has long been recommended before and during pregnancy to reduce the risk of neural tube defects. Factors influencing adherence to FA supplementation have been extensively evaluated, but little is known on the effect of parity. This study comes to examine the association between parity and maternal use of FA prior to and during pregnancy.

In this retrospective population-based study, we identified mothers (N=228 555) of all children (N=578 204) born between the years 2000 and 2016 among members of a large health provider in Israel. Data on FA supplementation purchases were obtained from centralised medical databases.

The median (IQR) total dose of FA purchased 12 months prior to child birth among previously nulliparous women (120 mg, 48-240) was significantly (p<0.001) higher than the dose purchased by women with one (90 mg (39-202)) and two prior births (84 mg (36-182)). The dose was even lower in women for three or more prior births (75 mg (36-165)). Despite the overall increasing secular trend in FA purchases during the study period, the negative relationship with parity remained.

Adherence to FA supplementation is negatively associated with parity. Women with increasing parity may be at higher risk for pregnancy complications associated with low FA levels. The results of this study may inform the design of interventions to specifically increase adherence to FA supplementations among multiparous women.