Epidemiology
DOI: 10.1111/1471-0528.12414 www.bjog.org
Maternal and health care determinants of preconceptional use of folic acid supplementation in France: results from the 2010 National Perinatal Survey J Tort,a,b N Lelong,a,b C Prunet,a,b B Khoshnood,a,b B Blondela,b a INSERM UMRS 953, Epidemiological Research Unit on Perinatal and Women’s and Children’s Health, Paris, France b UPMC University, Paris, France Correspondence: Dr B Blondel, INSERM U 953, Epidemiological Research Unit on Perinatal and Women’s and Children’s Health, Maternite´ de Port Royal, 53 avenue de l’Observatoire, 75014 Paris, France. Email
[email protected]
Accepted 29 June 2013. Published Online 10 September 2013.
Objectives To estimate the national prevalence and analyse
the factors associated with preconceptional folic acid supplementation, including maternal sociodemographic characteristics, region of residence, birth control use and chronic diseases requiring medical care before conception. Design Cross-sectional population-based study. Setting All maternity units in France. Population A nationally representative sample of women
giving birth in 2010 (n = 12,646). Methods Data came from mothers’ interviews 2–3 days
after delivery. Statistical analyses included multivariable logistic regressions. Main outcome measure Folic acid supplementation starting
at least 1 month before conception. Results 14.8% (95% confidence interval [95% CI] 14.2–15.4)
of women used folic acid before pregnancy; this percentage varied from 10.4% to 18.7% across regions. Supplementation was more frequent in primiparae, French citizens, women with higher
educational levels and those needing medical monitoring or treatment before conception. Women who stopped contraception to become pregnant (75% of our population) used folic acid more often (intrauterine device or implant: 19%, pill: 17%, other methods which did not need medical monitoring: 17%) than other women (7%). The adjusted odds ratios were 3.3 (95% CI 2.6–4.3) for intrauterine device and implant, 2.2 (95% CI 1.8–2.6) for pill and 1.9 (95% CI 1.5–2.4) for other methods, compared with women who did not use birth control. Conclusion The absence of preconceptional folic
acid supplementation for most women, even those needing consultations with healthcare professionals before pregnancy, shows that campaigns to promote folic acid supplementation should address not only women but also healthcare professionals involved in birth control and obstetric care before pregnancy. Keywords Chronic diseases, fertility treatments, folic acid, maternal characteristics, preconception, pregnancy planning, region.
Please cite this paper as: Tort J, Lelong N, Prunet C, Khoshnood B, Blondel B. Maternal and health care determinants of preconceptional use of folic acid supplementation in France: results from the 2010 National Perinatal Survey. BJOG 2013;120:1661–1667.
Introduction Neural tube defects (NTDs) are severe congenital malformations of the central nervous system, with a prevalence of approximately 1 per 1000, which lead to stillbirths, neonatal deaths and neurological disabilities.1 Termination of pregnancy is proposed to women in many countries, and 77% of pregnancies affected by NTDs were terminated in the early 2000s in Europe.2
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The efficacy of folic acid supplementation for primary prevention of NTDs is well established by several randomised controlled trials and a meta-analysis of these studies.3 Daily folic acid doses ranging from 0.4 to 4 mg, before pregnancy and for up to 12 weeks of gestation, decrease the risk of NTDs by up to 72% (relative risk 0.28; 95% confidence interval [95% CI] 0.15–0.52). Assuming a 50% efficacy rate, a conservative estimate of the number of cases avoided would be 450 per year in France.
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Most European countries have issued recommendations for folic acid supplementation, with or without a folaterich diet, during the periconceptional period.4 In France, it is recommended that women who intend to have a pregnancy begin folic acid supplementation at least 1 month before conception. Recommendations in Europe have generally had little if any effect on the trends in total prevalence of NTD since the 1990s, however.4,5 Numerous studies have estimated the frequency of folic acid use, but population-based studies are rare, especially at the national level,6,7 and almost never based on a representative sample of births.8 It is therefore difficult to know the extent to which recommendations have been adopted in the overall population of pregnant women. Moreover, studies of the determinants of folic acid intake have rarely considered the role of the medical providers consulted before conception.9,10 We hypothesised that, in addition to maternal sociodemographic characteristics,9 healthcare providers can play an important role in women’s decision to use folic acid supplementation before pregnancy. To test this hypothesis, we examined the prevalence of folic acid use for women who had to have specific medical visits before pregnancy. These women included, for example, those who had conceived following fertility treatments and those who had an intrauterine device (IUD). Using population-based data from a representative national sample of women giving birth in France, we sought to estimate the prevalence of folic acid supplementation begun before conception and to analyse the factors related to this supplementation, while distinguishing three categories of determinants: (i) maternal sociodemographic characteristics and region of residence, (ii) contraceptive methods and (iii) diseases or complications requiring medical visits or treatments before conception.
Methods Our study was based on data from the 2010 French National Perinatal Survey.11 National Perinatal Surveys are routine surveys designed to monitor perinatal health, medical care and health behaviour. They include all births (live and stillbirths) during a 1-week period in all maternity units. Women are interviewed in the maternity unit 2 or 3 days after delivery about their sociodemographic characteristics, health behaviours, birth planning and fertility treatments. Data on maternal health are collected from medical records. Comparisons for several perinatal indicators (e.g. maternal age, gestational age) available in birth certificate statistics and hospital discharge statistics show that the sample is representative of all births in 2010.11 In the 2010 survey, we asked women for the first time about folic acid use: ‘Did you use folic acid or vitamin B9 for prevention of NTDs for this pregnancy?’ If they
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answered yes, we asked them: ‘When did you start: more than 3 months before conception, between 1 and 3 months before conception, first month of pregnancy or after the first month?’ After exclusion of births in overseas territories and migrants who arrived during or in the 6 months before pregnancy, our sample included 14,266 women; 664 (4.6%) of them were not interviewed and 956 (6.7%) women did not know if they had used folic acid or when they began it. Finally, we analysed data for 12,646 women. We first assessed the prevalence of folic acid supplementation before conception and then studied the factors associated with it, comparing women who used folic acid supplementation before conception with those who did not or who started after conception. We studied three categories of determinants: (i) maternal characteristics, which included sociodemographic characteristics, smoking before pregnancy, body mass index and region of residence, (ii) birth control and (iii) fertility treatments and chronic diseases. Body mass index was studied because high prepregnancy body mass index is associated with an increased risk of NTDs.12 Pregnancy was considered planned if the woman stopped using her last contraceptive method to become pregnant and wanted a baby at the time she became pregnant. Birth control methods were categorised according to the need for medical services. We distinguished implants and IUD, which must be removed by a medical doctor, birth control pills, which require routine medical visits, and the other methods (mainly condom), which do not need medical visits. Three categories of chronic diseases or perinatal risk factors were considered, according to the woman’s need for medical care and monitoring before conception. The first category included those that necessitated folic acid supplementation, or a medical visit before pregnancy to adapt treatment or for screening (methylenetetrahydrofolate reductase mutation, previous pregnancy affected by NTDs, epilepsy, autoimmune diseases, HIV or hepatitis B virus infection, diabetes mellitus and recurrent miscarriages). The second category included maternal diseases that require regular medical follow up, such as high blood pressure, thyroid diseases, or a history of cancer. The third category included previous adverse pregnancy outcome or complications, including fetal or neonatal death, preterm birth, small-for-gestational-age newborn, gestational diabetes and gestational hypertension. Chi-square tests were performed in the bivariable analyses and logistic regressions for multivariable analyses. Data were analysed with SAS 9.2 (SAS Institute Inc., Cary, NC, USA).
Results Folic acid use began more than 3 months before pregnancy for 6.6% of women, and 1–3 months before pregnancy for
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Preconceptional use of folic acid in France
8.2%. In all, 14.8% (95% CI 14.2–15.4) of women started folic acid supplementation before pregnancy. Another 11.7% of women started folic acid use during the first month of pregnancy. Folic acid use before pregnancy was more frequent in older women, married or cohabiting women, European women, those who did not smoke or had stopped smoking for pregnancy and women with a body mass index
