Sarah Timmermans

Periconception folic acid supplementation, fetal growth and the risks of low birth weight and preterm birth: the Generation R Study

Countries worldwide, including the Netherlands, recommend that women planning pregnancy use a folic acid supplement during the periconception period. Some countries even fortify staple foods with folic acid. These recommendations mainly focus on the prevention of neural tube defects, despite increasing evidence that folic acid may also influence birth weight. We examined whether periconception folic acid supplementation affects fetal growth and the risks of low birth weight, small for gestational age (SGA) and preterm birth, in the Generation R Study in Rotterdam, the Netherlands. Main outcome measures were fetal growth measured in mid- and late pregnancy by ultrasound, birth weight, SGA and preterm birth in relation to periconception folic supplementation (0.4-0.5 mg). Data on 6353 pregnancies were available. Periconception folic acid supplementation was positively associated with fetal growth. Preconception folic acid supplementation was associated with 68 g higher birth weight (95 % CI 37.2, 99.0) and 13 g higher placental weight (95 % CI 1.1, 25.5), compared to no folic acid supplementation. In these analyses parity significantly modified the effect estimates. Start of folic acid supplementation after pregnancy confirmation was associated with a reduced risk of low birth weight (OR 0.61, 95 % CI 0.40, 0.94). Similarly, reduced risks for low birth weight and SGA were observed for women who started supplementation preconceptionally, compared to those who did not use folic acid (OR 0.43, 95 % CI 0.28, 0.69 and OR 0.40, 95 % CI 0.22, 0.72). In conclusion, periconception folic acid supplementation is associated with increased fetal growth resulting in higher placental and birth weight, and decreased risks of low birth weight and SGA.

Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: The generation R study

Please cite this paper as: Bergen N, Jaddoe V, Timmermans S, Hofman A, Lindemans J, Russcher H, Raat H, Steegers‐Theunissen R, Steegers E. Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study. BJOG 2012;119:739–751.

Maternal Thyroid Hormone Parameters during Early Pregnancy and Birth Weight: The Generation R Study

CONTEXT Maternal hyperthyroidism during pregnancy is associated with an increased risk of low birth weight, predisposing to neonatal morbidity and mortality. However, the effects of variation in maternal serum thyroid parameters within the normal range on birth weight are largely unknown. OBJECTIVE The aim was to study the effects of early pregnancy maternal serum thyroid parameters within the normal range on birth weight, as well as the relation between umbilical cord thyroid parameters and birth weight. DESIGN, SETTING, AND PARTICIPANTS In early pregnancy, serum TSH, FT4 (free T(4)), and thyroid peroxidase antibody levels were determined in 4464 pregnant women. Cord serum TSH and FT4 levels were determined in 2724 newborns. Small size for gestational age at birth (SGA) was defined as a gestational age-adjusted birth weight below the 2.5th percentile. The associations between normal-range maternal and cord thyroid parameters, birth weight, and SGA were studied using regression analyses. RESULTS In mothers with normal-range FT4 and TSH levels, higher maternal FT4 levels were associated with lower birth weight [β = -15.4 (3.6) g/pmol · liter, mean (SE); P = 1.6 × 10(-5)], as well as with an increased risk of SGA newborns [odds ratio (95% confidence interval) = 1.09 (1.01-1.17); P = 0.03]. Birth weight was positively associated with both cord TSH [β = 4.1 (1.4) g/mU · liter; P = 0.007] and FT4 levels [β = 23.0 (3.2) g/pmol · liter; P = 9.2 × 10(-13)]. CONCLUSIONS We show that maternal high-normal FT4 levels in early pregnancy are associated with lower birth weight and an increased risk of SGA newborns. Additionally, birth weight is positively associated with cord TSH and FT4 levels. These data demonstrate that even mild variation in thyroid function within the normal range can have important fetal consequences.

Determinants of folic acid use in early pregnancy in a multi-ethnic urban population in The Netherlands: The Generation R study

OBJECTIVE Recommendations on folic acid use to prevent neural tube defects have been launched in several countries. Adequate folic acid use seems to be low. This study assesses the prevalence of folic acid use and identifies its determinants. METHODS The study was embedded in the Generation R Study Rotterdam, the Netherlands, a population-based prospective cohort study between 2002 and 2006. Complete information of 6940 women was available. Information on folic acid use and potential determinants was obtained by questionnaires and physical examination. RESULTS Of all women 37% adequately used folic acid during the preconception period. Most important risk factors for inadequate use were unplanned pregnancy (OR 9.5, CI 7.2-12.4, p<0.001), low educational level (OR 2.5, CI 1.8-3.6, p<0.001) and non-western ethnicity, (OR 3.5, CI 2.9-4.3, p<0.001). After stratification for ethnicity, unplanned pregnancy remained the most important risk factor for inadequate use. Other risk factors for inadequate use were younger age, single marital status, smoking, multiparity (all p<0.001) and alcohol use (p<0.05). In contrast, previous spontaneous abortion decreased the risk of inadequate folic acid use (p<0.001). CONCLUSION Adequate preconception folic acid supplementation is still too low. Implementation of preconception programs and other public health strategies are strongly needed.

High Circulating Folate and Vitamin B-12 Concentrations in Women During Pregnancy Are Associated with Increased Prevalence of Atopic Dermatitis in Their Offspring

Recent studies suggest that in utero exposure of methyl donors influences programming of the fetal immune system in favor of development of allergic disease. The aim of this study was to assess whether the MTHFR C677T polymorphism, folic acid supplementation, and circulating folate and vitamin B-12 concentrations during pregnancy were associated with wheezing, shortness of breath, and atopic dermatitis in offspring. The study was a population-based birth cohort from fetal life until 48 mo (n = 8742). The use of folic acid supplementation during pregnancy was assessed by questionnaire. Plasma folate and serum vitamin B-12 concentrations and the MTHFR C677T polymorphism were available from blood collected in early pregnancy. Atopic dermatitis, wheezing, and shortness of breath in the offspring were assessed by parental-derived questionnaires at 12, 24, 36, and 48 mo. Maternal folate >16.2 nmol/L and vitamin B-12 >178 pmol/L were positively associated with the development of atopic dermatitis [adjusted OR: 1.18 (95% CI: 1.05-1.33) and adjusted OR: 1.30 (95% CI: 1.06-1.60) for the highest quartiles of folate and vitamin B-12 concentrations, respectively] but not with wheezing and shortness of breath. Maternal MTHFR C677T polymorphism and folic acid supplementation were not associated with wheezing, shortness of breath, and atopic dermatitis. No interactions were found by age, family history of atopy, folic acid supplementation, MTHFR C677T polymorphism, or maternal smoking (P-interaction > 0.10). High folate and vitamin B-12 levels during pregnancy are associated with increased prevalence of atopic dermatitis in the offspring. Potential risks of high folate and vitamin B-12 concentrations on allergic outcomes should be evaluated when discussing mandatory fortification programs.

Folic acid is positively associated with uteroplacental vascular resistance: the Generation R study.

BACKGROUND AND AIMS Periconception folic acid supplementation may influence early placentation processes and thereby the occurrence of hypertensive pregnancy disorders. For this reason we examined the associations between periconception folic acid supplementation and uteroplacental vascular resistance, blood pressure, and the risks of gestational hypertension and preeclampsia, in 5993 pregnant women, participating in a population-based cohort study. METHODS AND RESULTS Folic acid supplementation was assessed by questionnaire. Mean pulsatility index (PI) and resistance index (RI) of the uterine (UtA) and umbilical arteries (UmA) were measured by Doppler ultrasound in mid- and late pregnancy. Systolic and diastolic blood pressures (SBP, DBP) were measured in early, mid- and late pregnancy. Compared to women who did not use folic acid, preconception folic acid users had a slightly lower UtA-RI in mid-pregnancy [β -0.02, 95% confidence interval (CI) -0.03, -0.01] and late pregnancy [β -0.02, 95% CI -0.03, -0.001], a lower UtA-PI in mid-pregnancy [β -0.06, 95% CI -0.1, -0.03] and late pregnancy [β -0.03, 95% CI -0.05, -0.01], as well as tendencies towards a lower UmA-PI in mid-pregnancy [β -0.02, 95% CI -0.04, -0.001] and late pregnancy [β -0.01, 95% CI -0.02, 0.01]. Additionally, these women had slightly higher SBP and DBP throughout pregnancy. Neither the patterns of blood-pressure change during pregnancy, nor the risk of gestational hypertension and preeclampsia differed between the folic acid categories. CONCLUSION Periconception folic acid supplementation is associated with lower uteroplacental vascular resistance and higher blood pressures during pregnancy. The effects are small and within physiologic ranges and seem not associated with the risk of hypertensive pregnancy disorders.

Angiogenic and fibrinolytic factors in blood during the first half of pregnancy and adverse pregnancy outcomes.

OBJECTIVE: To estimate whether the imbalance of angiogenic factors (soluble fms-like tyrosine kinase-1, placental growth factor) and fibrinolytic factors (plasminogen activator inhibitor-2 [PAI-2]) might affect placentation in early pregnancy. METHODS: We studied the associations of maternal soluble fms-like tyrosine kinase-1, placental growth factor, and PAI-2 concentrations in the first trimester (before 18 weeks of gestation) and soluble fms-like tyrosine kinase-1 and placental growth factor concentrations in the second trimester (18–25 weeks of gestation) with placental function and adverse pregnancy outcomes. This study was embedded in a population-based prospective cohort study. Data were used from 7,519 women. Biomarker concentrations were divided into deciles and evaluated in multivariable linear and logistic regression models. RESULTS: First-trimester high soluble fms-like tyrosine kinase-1 was associated with a 5.2% lower uterine artery index in the second-trimester and a 1.6% higher birth weight (55 g, confidence interval [CI] 15–95). Neither in the first nor in the second trimester were soluble fms-like tyrosine kinase-1 concentrations significantly associated with preeclampsia. First-trimester low placental growth factor was associated with a 6.1% higher uterine artery index and a 3.4% lower birth weight (−115 g, CI −157 to −74). First-trimester low placental growth factor was associated with fetal growth restriction (odds ratio [OR] 2.62, CI 1.68–4.08) and preeclampsia (OR 2.46, CI 1.49–4.08). First-trimester low PAI-2 was associated with a 1.9% higher uterine artery index and a 2.7% lower birth weight (−94 g, CI −136 to −51). First-trimester low PAI-2 was associated with a higher risk of fetal growth restriction (OR 2.22, CI 1.39–3.55). CONCLUSION: First-half-of-pregnancy concentrations of soluble fms-like tyrosine kinase-1, placental growth factor, and PAI-2 are associated with uteroplacental vascular resistance, placental weight, and birth weight. Moreover, first-trimester placental growth factor and PAI-2 are associated with an increased risk of adverse pregnancy outcomes. LEVEL OF EVIDENCE: II

Folic Acid Supplements Modify the Adverse Effects of Maternal Smoking on Fetal Growth and Neonatal Complications

Maternal smoking during pregnancy leads to increased risks of neonatal complications. The use of folic acid supplements might reduce the adverse effects of smoking. We examined whether folic acid supplement use modifies the associations of maternal smoking with first trimester plasma homocysteine concentrations, fetal growth characteristics, and risks of neonatal complications. The associations were studied in 6294 mothers participating in a prospective population-based cohort study in The Netherlands. Main outcomes measurements were first trimester plasma homocysteine concentrations, fetal growth characteristics, and neonatal complications, including preterm birth, low birth weight, and small-size-for-gestational-age. Continued maternal smoking was associated with higher first trimester plasma homocysteine concentrations [difference 0.52 μmol/L (95% range = 0.20, 2.14)], lower third trimester fetal weight (difference -44 g (95% CI = -57, -31)], and birth weight [difference -148 g (95% CI = -179, -118)]. There were significant interactions between maternal smoking and folic acid supplements on all outcome measures (all P-interaction < 0.040). Among mothers who continued smoking during pregnancy, those who did not use folic acid supplements had the highest risk of delivering a child with low birth weight [OR = 3.45 (95% CI = 1.25, 9.54)] compared to those who did use periconceptional folic acid supplements. No significant effects were observed for the risks of preterm birth and small-size-for-gestational-age at birth. Our results suggest that some adverse effects of maternal smoking on fetal growth and neonatal outcomes might be reduced by the use of folic acid supplements. The observed interaction seems to be mainly driven by smoking in the first trimester only.

Major dietary patterns and blood pressure patterns during pregnancy: the Generation R Study

OBJECTIVE We sought to evaluate associations between dietary patterns and systolic blood pressure (SBP) and diastolic blood pressure during pregnancy. STUDY DESIGN This was a prospective study of 3187 pregnant women. Participants completed a food-frequency questionnaire in early pregnancy. The Mediterranean dietary pattern, comprising high intake of vegetables, vegetable oils, pasta, fish, and legumes, and the Traditional dietary pattern, comprising high intake of meat and potatoes, were identified using factor analysis. RESULTS A higher SBP was observed among mothers with high Traditional pattern adherence. Low adherence to the Mediterranean pattern was also associated with higher SBP but only in early and mid pregnancy. A higher diastolic blood pressure throughout pregnancy was observed in mothers with high adherence to the Traditional pattern and low adherence to the Mediterranean pattern. These effect estimates were most pronounced in mid pregnancy. CONCLUSION Low adherence to a Mediterranean and high adherence to a Traditional dietary pattern is associated with a higher blood pressure in pregnancy.

Maternal fish consumption, fetal growth and the risks of neonatal complications: The Generation R Study

Maternal fish consumption during pregnancy has been suggested to affect birth outcomes. Previous studies mainly focused on birth outcomes and did not study fetal growth during pregnancy. In a prospective cohort study from early pregnancy onwards in The Netherlands, we assessed the associations of first-trimester maternal total-fish, lean-fish, fatty-fish and shellfish consumption with fetal growth characteristics in the second and third trimesters, growth characteristics at birth and the risks of neonatal complications, including pre-term birth, low birth weight and small for gestational age. In total, 3380 mothers completed a 293-item semi-quantitative FFQ to obtain information about fish consumption during the first trimester of pregnancy. Head circumference, femur length and fetal weight were estimated in the second and third trimesters by ultrasound. Information about birth anthropometrics and neonatal complications was available from hospital and midwife registries. Maternal older age, higher educational level, folic acid supplement use, alcohol use and not smoking were associated with higher fish consumption (P < 0·01). After adjustment, we observed no consistent associations of maternal total-fish consumption or specific consumption of lean fish, fatty fish or shellfish with fetal growth characteristics in the second and third trimesters and at birth. Likewise, total-fish consumption or specific consumption of any type of fish was not consistently associated with the risks of neonatal complications. These findings suggest that in a population with a relatively low fish intake, consumption of lean fish, fatty fish or shellfish in the first trimester is not associated with fetal growth or the risks of neonatal complications.