Abstract：
BACKGROUND: Living in high-altitude regions has been associated with a higher prevalence of some birth defects. Moderate altitudes (1500-2500 m) have been associated with some congenital heart diseases and low birth weight. However, no studies have been conducted for other isolated congenital malformations.
OBJECTIVE: To estimate the prevalence at birth of isolated congenital malformations in low and moderate altitudes and to determine if moderate altitudes are a risk factor, such as high altitudes, for isolated congenital malformations adjusted for other factors.
METHODS: The study consisted of a case-control multicenter-multiregional study of 13 isolated congenital malformations. Cases included live births with isolated congenital malformations and controls at low (10-1433 m) and moderate altitudes (1511-2426 m) from a Mexican registry from January 1978 to December 2019. Prevalence per 10,000 (95% CI) per altitude group was estimated. We performed unadjusted and adjusted logistic regression models (adjusted for maternal age, parity, malformed relatives, socioeconomic level, and maternal diabetes) for each isolated congenital malformation.
RESULTS: Hydrocephaly and microtia had a higher at-birth prevalence, and spina bifida, preauricular tag, and gastroschisis showed a lower at-birth prevalence in moderate altitudes. Moderate altitudes were a risk factor for hydrocephaly (aOR 1.39), microtia (aOR 1.60), cleft-lip-palate (aOR 1.27), and polydactyly (aOR 1.32) and a protective effect for spina bifida (aOR 0.87) compared with low altitudes.
CONCLUSIONS: Our findings provide evidence that moderate altitudes as higher altitudes are an associated risk or protective factor to some isolated congenital malformations, suggesting a possible gradient effect.
OBJECTIVE: To estimate the prevalence at birth of isolated congenital malformations in low and moderate altitudes and to determine if moderate altitudes are a risk factor, such as high altitudes, for isolated congenital malformations adjusted for other factors.
METHODS: The study consisted of a case-control multicenter-multiregional study of 13 isolated congenital malformations. Cases included live births with isolated congenital malformations and controls at low (10-1433 m) and moderate altitudes (1511-2426 m) from a Mexican registry from January 1978 to December 2019. Prevalence per 10,000 (95% CI) per altitude group was estimated. We performed unadjusted and adjusted logistic regression models (adjusted for maternal age, parity, malformed relatives, socioeconomic level, and maternal diabetes) for each isolated congenital malformation.
RESULTS: Hydrocephaly and microtia had a higher at-birth prevalence, and spina bifida, preauricular tag, and gastroschisis showed a lower at-birth prevalence in moderate altitudes. Moderate altitudes were a risk factor for hydrocephaly (aOR 1.39), microtia (aOR 1.60), cleft-lip-palate (aOR 1.27), and polydactyly (aOR 1.32) and a protective effect for spina bifida (aOR 0.87) compared with low altitudes.
CONCLUSIONS: Our findings provide evidence that moderate altitudes as higher altitudes are an associated risk or protective factor to some isolated congenital malformations, suggesting a possible gradient effect.
摘要：
背景：生活在高海拔地区与某些出生缺陷的患病率较高有关。中等海拔（1500-2500m）与一些先天性心脏病和低出生体重有关。然而,尚未对其他孤立的先天性畸形进行研究。
目的：评估在低海拔和中等海拔地区出生时孤立的先天性畸形的患病率，并确定中等海拔是否是一个危险因素，比如高海拔，针对其他因素调整后的孤立先天性畸形。
方法：该研究包括13例孤立的先天性畸形的病例对照多中心多区域研究。病例包括1978年1月至2019年12月墨西哥登记处低海拔（10-1433m）和中等海拔（1511-2426m）的孤立先天性畸形活产和对照。估计每个海拔组的每10,000人的患病率（95％CI）。我们进行了未调整和调整的逻辑回归模型(调整了产妇年龄，奇偶校验，畸形的亲戚，社会经济水平,和母体糖尿病）对于每个孤立的先天性畸形。
结果：脑积水和小耳畸形在出生时的患病率较高，和脊柱裂,耳前标记,腹裂在中等海拔地区的出生患病率较低。中度海拔高度是脑积水的危险因素（aOR1.39），microtia(aOR1.60)，唇腭裂（aOR1.27），与低海拔相比，多指（aOR1.32）和对脊柱裂的保护作用（aOR0.87）。
结论：我们的发现提供了证据，表明中等海拔高度和较高海拔高度是一些孤立的先天性畸形的相关风险或保护因素，暗示可能的梯度效应。
目的：评估在低海拔和中等海拔地区出生时孤立的先天性畸形的患病率，并确定中等海拔是否是一个危险因素，比如高海拔，针对其他因素调整后的孤立先天性畸形。
方法：该研究包括13例孤立的先天性畸形的病例对照多中心多区域研究。病例包括1978年1月至2019年12月墨西哥登记处低海拔（10-1433m）和中等海拔（1511-2426m）的孤立先天性畸形活产和对照。估计每个海拔组的每10,000人的患病率（95％CI）。我们进行了未调整和调整的逻辑回归模型(调整了产妇年龄，奇偶校验，畸形的亲戚，社会经济水平,和母体糖尿病）对于每个孤立的先天性畸形。
结果：脑积水和小耳畸形在出生时的患病率较高，和脊柱裂,耳前标记,腹裂在中等海拔地区的出生患病率较低。中度海拔高度是脑积水的危险因素（aOR1.39），microtia(aOR1.60)，唇腭裂（aOR1.27），与低海拔相比，多指（aOR1.32）和对脊柱裂的保护作用（aOR0.87）。
结论：我们的发现提供了证据，表明中等海拔高度和较高海拔高度是一些孤立的先天性畸形的相关风险或保护因素，暗示可能的梯度效应。
