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.