Use of high doses of folic acid supplements in pregnant women in Spain: an INMA cohort study

OBJECTIVES We examined the use of low (<400 μg/day, including no use) and high folic acid supplement (FAS) dosages (≥1000 μg/day) among pregnant women in Spain, and explored factors associated with the use of these non-recommended dosages. DESIGN Population-based cohort study. SETTING Spain. PARTICIPANTS We analysed data from 2332 pregnant women of the INMA study, a prospective mother-child cohort study in Spain. MAIN OUTCOME MEASURES We assessed usual dietary folate and the use of FAS from preconception to the 3rd month (first period) and from the 4th to the 7th month (second period), using a validated food frequency questionnaire. We used multinomial logistic regression to estimate relative risk ratios (RRRs). RESULTS Over a half of the women used low dosages of FAS in the first and second period while 29% and 17% took high dosages of FAS, respectively. In the first period, tobacco smoking (RRR=1.63), alcohol intake (RRR=1.40), multiparous (RRR=1.44), unplanned pregnancy (RRR=4.20) and previous spontaneous abortion (RRR=0.58, lower use of high FAS dosages among those with previous abortions) were significantly associated with low FAS dosages. Alcohol consumption (RRR=1.42), unplanned pregnancy (RRR=2.66) and previous spontaneous abortion (RRR=0.68) were associated with high dosage use. In the second period, only tobacco smoking was significantly associated with high FAS dosage use (RRR=0.67). CONCLUSIONS A high proportion of pregnant women did not reach the recommended dosages of FAS in periconception and a considerable proportion also used FAS dosages ≥1000 μg/day. Action should be planned by the Health Care System and health professionals to improve the appropriate periconceptional use of FAS, taking into consideration the associated factors.