A Case-Control Study of Maternal Occupation and the Risk of Orofacial Clefts

Risk of orofacial clefts in relation to maternal body mass index, diabetes and hypertension

BACKGROUND

To investigate if maternal body mass index, diabetes and hypertension are associated with orofacial clefts.

METHODS

Case-control study. Information from 53,188 live births with and without orofacial cleft registered at USA Vital Statistics Natality Birth Data between 2017 and 2021. Case group consisted of all affected live births diagnosed with orofacial clefts (13,297 cases). Comparison group consisted of 39,891 live births without clefts or any other congenital malformation. Information about orofacial cleft cases were compared with the comparison group. The unadjusted and adjusted Odds Ratios were estimated to evaluate the strength of association between mother's pre-pregnancy body mass index, maternal diabetes and hypertension and orofacial cleft occurrence, assuming a p value < 0.05 and 95% confidence intervals (95% C.I.) for statistically significant differences.

RESULTS

Mother's pre-pregnancy body mass index, maternal diabetes and maternal hypertension are conditions associated with an increased risk of orofacial cleft development in the child (OR = 1.08, p = 0.004, 95% C.I. = 1.024-1.149; OR = 1.32, 95%, p = 0.000, 95% C.I. = 1.202-1.444; and OR = 1.35, p = 0.000, 95% C.I. = 1.239-1.484; respectively). Maternal ethnicity, sex of infant, and cigarette smoking pregnancy remained as covariates after adjustments in all logistic regression models.

CONCLUSION

Due to the increased prevalence of obesity, diabetes, and hypertension, and also to their association with congenital malformations, such as clefts, it is recommended that mothers planning to become pregnant to follow healthy habits, maintain healthy weight, and be screened for possible diabetes or hypertension prior to conception and early in pregnancy.

Levels of uranium and thorium in maternal scalp hair and risk of orofacial clefts in offspring

Uranium and thorium are common radioactive elements that exist in the environment. However, few environmental epidemiological studies have focused on their possible effects on congenital malformations. Here, we explored the association between uranium and thorium concentrations in maternal scalp hair grown from 3 months before to 3 months after conception, namely during the periconceptional period and the risk of orofacial clefts (OFCs) in offspring. Our study included 153 women whose pregnancies were affected by OFCs (cases) and 601 women who delivered infants without birth defects (controls) from four provinces in China. Face-to-face interviews were used to collect sociodemographic characteristics with a structured questionnaire. Concentrations of uranium and thorium in maternal scalp hair grown during the periconceptional period were detected using inductively coupled plasma-mass spectrometry. The risk of OFCs in association with higher concentrations of the two radioactive elements was estimated using odds ratios (ORs) and 95% confidence intervals (CIs) while adjusting for potential confounding factors. The levels of uranium and thorium in maternal hair were in agreement with the published literature. After adjusting for several confounders, the ORs of thorium in the highest, upper, and lower quartile versus the lowest quartile were 2.63 (95% CI, 1.41-4.92), 1.98 (95% CI, 1.03-3.79), and 2.73 (95% CI, 1.46-5.12), respectively. No association was found between levels of uranium and the risk of OFCs. Maternal periconceptional exposure to thorium may be a risk factor for OFCs in offspring.

Maternal occupation and the risk of neural tube defects in offspring

We evaluated the association between maternal occupation and the risk of neural tube defects (NTDs) in offspring. Data for 491 nonsyndromic cases were obtained from the Texas Birth Defects Registry for deliveries between 1999 and 2009. We randomly selected 2,291 controls among all live births in Texas during this time. Maternal occupations were classified using automated software and manual assignment. Multivariable logistic regression analyses were used to examine the relationship between maternal occupation and risk for any NTD, adjusting for maternal race/ethnicity, any diabetes, and maternal body mass index. These analyses were repeated for spina bifida specifically. Some maternal occupations, particularly those related to business/finance, health care practice, and cleaning/maintenance, were significantly associated with increased risk of spina bifida and/or any NTD. Further research is needed to identify the specific occupational exposures related to NTD risk.

Maternal occupational physical activity and risk for orofacial clefts

OBJECTIVES

To perform a case-control study of maternal occupational physical activity and risk for orofacial clefts in Texas during 1999-2009.

METHODS

We used logistic regression to assess 14 measures of physical activity estimated from a job exposure matrix, using the maternal occupation reported on the birth certificate, among 887 children with cleft lip with or without cleft palate (CLP), 436 children with cleft palate only (CP), and 1932 controls.

RESULTS

After adjusting for several potential confounders, seven measures of physical activity (as a categorical and/or continuous variable) were significantly associated with CLP, CP, or both. Positive associations were seen for keeping balance, kneeling, standing, and walking/running (odds ratio 95% confidence interval range 1.0-1.9 for fourth versus first quartile). A significant positive trend was also seen for bending/twisting. Negative associations were seen for repetitive motion and sitting.

CONCLUSIONS

Maternal occupational physical activity may be related to the etiology of orofacial clefts.