Impact of Periconceptional Use of Nitrosatable Drugs on the Risk of Neural Tube Defects

Prenatal exposure to nitrosatable drugs and timing of puberty in sons and daughters: A nationwide cohort study

BACKGROUND

N-nitroso compounds (NOCs) can be formed by endogenous reactions between nitrosatable drugs and nitrite. Animal studies have found that several NOCs are teratogenic, and epidemiological studies report associations between prenatal exposure to nitrosatable drugs and adverse birth outcomes. It is unknown whether prenatal exposure to nitrosatable drugs is harmful to the child's reproductive health, including pubertal development.

OBJECTIVES

We investigated whether prenatal exposure to nitrosatable drugs was associated with timing of puberty and whether nitrate, nitrite and antioxidant intake modified any association.

METHODS

The population-based Danish National Birth Cohort (DNBC) Puberty Cohort, which includes 15,819 children, was used to investigate the association between prenatal exposure to nitrosatable drugs and timing of puberty. Around gestational week 11 and gestational week 18, mothers provided information about drug use during pregnancy. The children's self-reported information on onset of pubertal milestones was collected every six months from 11 years of age and throughout puberty. To investigate potential effect modification by nitrite, nitrate and antioxidant intake, information on these factors was obtained from a food frequency questionnaire completed by the mothers in gestational week 25, and information on nitrate concentration in maternal drinking water at her residential address was obtained from monitoring data from public waterworks. Data were analysed using a multivariable regression model for interval-censored data estimating difference in months in timing of puberty between exposure groups.

RESULTS

A total of 2,715 children were prenatally exposed to nitrosatable drugs. We did not find an association between prenatal exposure to nitrosatable drugs and timing of puberty. This finding was supported by null-findings in the following sub-analyses investigating: 1. subtypes of nitrosatable drugs (secondary and tertiary amines and amides), 2. dose-dependency (duration of drug intake), 3. effect modification by maternal intake of nitrate, nitrite, and antioxidants. 4. confounding by indication.

CONCLUSIONS

Prenatal exposure to nitrosatable drugs was not associated with timing of puberty. Nitrosatable drugs are commonly used drugs in pregnancy, and further research is needed to allow firm conclusions on the potential effect of prenatal exposure to nitrosatable drugs on the child's reproductive health.

Drinking water nitrate and risk of pregnancy loss: a nationwide cohort study

BACKGROUND

Nitrate contamination is seen in drinking water worldwide. Nitrate may pass the placental barrier. Despite suggestive evidence of fetal harm, the potential association between nitrate exposure from drinking water and pregnancy loss remains to be studied. We aimed to investigate if nitrate in drinking water was associated with the risk of pregnancy loss.

METHODS

We conducted a nationwide cohort study of 100,410 pregnancies (enrolled around gestational week 11) in the Danish National Birth Cohort (DNBC) during 1996-2002. Spontaneous pregnancy losses before gestational week 22 were ascertained from the Danish National Patient Registry and DNBC pregnancy interviews. Using the national drinking water quality-monitoring database Jupiter, we estimated the individual and time-specific nitrate exposure by linking geocoded maternal residential addresses with water supply areas. The nitrate exposure was analyzed in spline models using a log-transformed continuous level or classified into five categories. We used Cox proportional hazards models to estimate associations between nitrate and pregnancy loss and used gestational age (days) as the time scale, adjusting for demographic, health, and lifestyle variables.

RESULTS

No consistent associations were found when investigating the exposure as a categorical variable and null findings were also found in trimester specific analyses. In the spline model using the continuous exposure variable, a modestly increased hazard of pregnancy loss was observed for the first trimester at nitrate exposures between 1 and 10 mg/L, with the highest. adjusted hazard ratio at 5 mg/L of nitrate of 1.16 (95% CI: 1.01, 1.34). This trend was attenuated in the higher exposure ranges.

CONCLUSION

No association was seen between drinking water nitrate and the risk of pregnancy loss when investigating the exposure as a categorical variable. When we modelled the exposure as a continuous variable, a dose-dependent association was found between drinking water nitrate exposure in the first trimester and the risk of pregnancy loss. Very early pregnancy losses were not considered in this study, and whether survival bias influenced the results should be further explored.

Racial/Ethnic Differences in Prenatal Supplement and Medication Use in Low-Risk Pregnant Women

OBJECTIVE

This study aimed to describe the overall quantity and type of supplements and medications used during pregnancy in a low-risk cohort and to examine any racial/ethnic differences in intake.

STUDY DESIGN

We used data from 2,164 racially/ethnically diverse, nonobese, and low-risk pregnant women participating without pre-pregnancy chronic conditions in a prospective cohort study at 12 sites across the United States. Medication data were self-reported as free text in enrollment, follow-up visit questionnaires, and abstracted from medical records at delivery. Supplements and medications data were mapped to their active ingredients and categorized into corresponding classes using the Slone Drug Dictionary. The total number and classes of supplements and medications consumed during pregnancy were calculated. Modified Poisson regression models were used to estimate the racial/ethnic differences in supplements and medications intake. All models were adjusted for maternal sociodemographic factors and study site.

RESULTS

98% of women took at least one supplement during pregnancy, with prenatal vitamins/multivitamins being most common. While only 31% reported taking no medications during pregnancy, 23% took one, 18% took two, and 28% took three or more. The percentage of women taking at least one medication during pregnancy was highest among non-Hispanic white women and lowest among Asians (84 vs. 55%, p < 0.001). All racial/ethnic groups reported taking the same top four medication classes including central nervous system agents, gastrointestinal drugs, anti-infective agents, and antihistamines. Compared with non-Hispanic white women, Hispanic (adjusted relative risk [aRR]: 0.84, 95% confidence interval [CI]: 0.71-0.98), and Asian women (aRR: 0.83, 95% CI: 0.70-0.98) were less likely to take central nervous system agents, as well as gastrointestinal drugs (Hispanics aRR: 0.79, 95% CI: 0.66-0.94; Asians aRR = 0.75, 95% CI: 0.63-0.90), and antihistamines (Hispanics aRR: 0.65, 95% CI: 0.47-0.92).

CONCLUSION

Supplement intake was nearly universal. Medication use was also common among this low-risk pregnancy cohort and differed by race/ethnicity.

GOV IDENTIFIER

NCT00912132.

KEY POINTS

· In women without chronic conditions, medication use is common.. · Racial/ethnic differences exist in prenatal medications use.. · Almost all women use supplements during pregnancy..

Prenatal nitrosatable prescription drug intake, drinking water nitrate, and the risk of stillbirth: a register- and population-based cohort of Danish pregnancies, 1997-2017

BACKGROUND

Nitrosatable drugs commonly prescribed during pregnancy can react with nitrite to form N-nitroso compounds which have been associated with an increased risk of stillbirth. Whether maternal residential drinking water nitrate modifies this association is unknown. We investigated, if household drinking water nitrate was associated with stillbirth, and if it modified the association between nitrosatable prescription drug intake and the risk of stillbirth.

METHODS

We conducted an individual-level register- and population-based cohort study using 652,810 women with the first recorded singleton pregnancy in the Danish Medical Birth Registry between 1997 and 2017. Nitrosatable drug exposure was recorded by use of the Danish National Patient Registry defined as women with a first redeemed prescription of a nitrosatable drug the first 22 weeks of pregnancy. The reference group was women with no redeemed prescription of a nitrosatable drug in this period. The average individual drinking water nitrate concentration level (mg/L) was calculated in the same period. We categorized nitrosatable drugs as secondary amines, tertiary amines, and amides. Cox hazard regression was used to estimate crude and adjusted hazard ratios with 95% confidence intervals for stillbirth stratified into five categories of nitrate concentrations: ≤1 mg/L, > 1- ≤ 2 mg/L, > 2- ≤ 5 mg/L, > 5- ≤ 25 mg/L, and > 25 mg/L.

RESULTS

Drinking water nitrate exposure in the population was not associated with the risk of stillbirth. Among 100,244 women who had a nitrosatable prescription drug redeemed ≤22 weeks of pregnancy of pregnancy, 418 (0.42%) had a stillbirth compared to 1993 stillbirths (0.36%) among 552,566 referent women. Women with any nitrosatable prescription drug intake and > 1- ≤ 2 mg/L nitrate concentration had an increased risk of stillbirth [adjusted hazard ratio 1.55 (95% confidence interval, 1.15-2.09)] compared with referent women. In the stratified analyses, the highest risk of stillbirth was found among women with secondary amine intake and > 25 mg/L nitrate concentrations [adjusted hazard ratio 3.11 (95% CI, 1.08-8.94)].

CONCLUSIONS

The association between nitrosatable prescription drug intake and the risk of stillbirth may depend on the level of nitrate in household drinking water. Evaluations of the effect of nitrosatable drug intake on perinatal outcomes might consider nitrate exposure from drinking water.

A comparison of the maternal levels of serum proprotein convertase subtilisin/kexin type 9 in pregnant women with the complication of fetal open neural tube defects

It was aimed to evaluate the levels of maternal serum proprotein convertase subtilisin/kexin type 9 (PCSK9) in pregnant women with a fetus diagnosed with open neural tube defects (NTDs). This case-control study included 38 pregnant women carrying fetuses with open NTDs and 44 age-matched, pregnant women with no specified risk factors. Comparisons were made of the groups in respect of demographic and clinical data and PCSK9 levels. To examine the performance of PCSK9 levels in the prediction of fetal open NTDs, receiver operating characteristic (ROC) curve analysis was used. In the first and second trimesters, PCSK9 levels were determined to be lower in the NTD group than in the control group (p = 0.010 and p = 0.015, respectively). In the first trimester, the lower PCSK9 levels in the NTD group were not statistically significant (p = 0.575). In the second trimester, the ROC curve value with the best balance of sensitivity/specificity for PCSK9 was 71.9 ng/ml (84.6% sensitivity, 51.7% specificity) and in the first and second trimester combined, 74.4 ng/ml (81.6% sensitivity, 45.5% specificity) (p = 0.015, p = 0.036, respectively). PCSK9 may be involved in the etiopathogenesis of open NTDs at the critical steps of fetal neuronal differentiation. Although it has limitations, PCSK9 may be used as an additional biomarker for the screening of NTDs.

Organoids as a new model system to study neural tube defects

The neural tube is the first critically important structure that develops in the embryo. It serves as the primordium of the central nervous system; therefore, the proper formation of the neural tube is essential to the developing organism. Neural tube defects (NTDs) are severe congenital defects caused by failed neural tube closure during early embryogenesis. The pathogenesis of NTDs is complicated and still not fully understood even after decades of research. While it is an ethically impossible proposition to investigate the in vivo formation process of the neural tube in human embryos, a newly developed technology involving the creation of neural tube organoids serves as an excellent model system with which to study human neural tube formation and the occurrence of NTDs. Herein we reviewed the recent literature on the process of neural tube formation, the progress of NTDs investigations, and particularly the exciting potential to use neural tube organoids to model the cellular and molecular mechanisms underlying the etiology of NTDs.

Comparison of fetal growth by maternal prenatal acetaminophen use

BACKGROUND

Equivocal findings exist regarding prenatal acetaminophen use and various adverse neonatal and childhood health outcomes, though with no data on fetal growth. We evaluated whether fetal growth differed by maternal acetaminophen use.

METHODS

Racially diverse, healthy women with low-risk antenatal profiles from 12 US clinical centers were enrolled in a prospective cohort study and followed until delivery. Ultrasound measurements of fetal parameters and self-reported prenatal acetaminophen use were collected at enrollment and up to five follow-up visits. Prenatal acetaminophen use was dichotomized as none or any.

RESULTS

Among 2291 women, 932 (41%) reported the use of acetaminophen medications during the current pregnancy. Estimated growth curves of fetal parameters did not differ between women reporting use of any medication containing acetaminophen and women with no reported use of the same.

CONCLUSION

Among healthy mothers with low-risk pregnancies, maternal acetaminophen use was not associated with alterations in fetal growth.

Nitrosatable drug exposure during pregnancy and risk of stillbirth

PURPOSE

Nitrosatable drugs can react with nitrite in the stomach and form N-nitroso compounds. Exposure to nitrosatable drugs has been associated with congenital malformations and preterm birth, but use during pregnancy as a cause of fetal death is not well-known. We examined if prenatally nitrosatable drug use is associated with risk of stillbirth.

METHODS

A nationwide cohort was conducted using 554 844 women with singleton and first recorded pregnancies regardless of previous pregnancy history from the Danish Medical Birth Register from 1996 to 2015. Exposure was recorded by use of the Danish National Prescription Register and defined as women who had redeemed a prescribed nitrosatable drug in the first 22 weeks of pregnancy. The reference group was women with no redeemed prescribed nitrosatable drug in this time period. We categorized nitrosatable drugs as secondary amines, tertiary amines, and amides. Cox hazard regression was used to estimate crude and adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for stillbirth.

RESULTS

Among the 84 720 exposed women, 348 had a stillbirth compared with 1690 stillbirths among the 470 124 unexposed women. Women who used any prescribed nitrosatable drug were more likely to have a stillbirth compared with unexposed women (aHRs 1.24; 95% CI, 1.03-1.49).

CONCLUSION

Nitrosatable drug use during the first 22 weeks of pregnancy might increase risk of stillbirth. The findings should be interpreted cautiously because of important unmeasured factors that might influence the observed association, including maternal vitamin C intake, dietary, and other sources of nitrate/nitrite intake.