Perin Jamie, Amouzou Agbessi, Walker Neff
Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, USA.
BMC Public Health. 2017 Nov 7;17(Suppl 4):786. doi: 10.1186/s12889-017-4741-6.
Increased contraceptive use has been associated with a decrease in high parity births, births that occur close together in time, and births to very young or to older women. These types of births are also associated with high risk of under-five mortality. Previous studies have looked at the change in the level of contraception use and the average change in these types of high-risk births. We aim to predict the distribution of births in a specific country when there is a change in the level and method of modern contraception.
We used data from full birth histories and modern contraceptive use from 207 nationally representative Demographic and Health Surveys covering 71 countries to describe the distribution of births in each survey based on birth order, preceding birth space, and mother's age at birth. We estimated the ecologic associations between the prevalence and method-mix of modern contraceptives and the proportion of births in each category. Hierarchical modelling was applied to these aggregated cross sectional proportions, so that random effects were estimated for countries with multiple surveys. We use these results to predict the change in type of births associated with scaling up modern contraception in three different scenarios.
We observed marked differences between regions, in the absolute rates of contraception, the types of contraceptives in use, and in the distribution of type of birth. Contraceptive method-mix was a significant determinant of proportion of high-risk births, especially for birth spacing, but also for mother's age and parity. Increased use of modern contraceptives is especially predictive of reduced parity and more births with longer preceding space. However, increased contraception alone is not associated with fewer births to women younger than 18 years or a decrease in short-spaced births.
Both the level and the type of contraception are important factors in determining the effects of family planning on changes in distribution of high-risk births. The best predictions for how birth risk changes with increased modern contraception and for different contraception methods allow for more nuanced predictions specific to each country and can aid better planning for the scaling up of modern contraception.
避孕措施使用的增加与多胎生育减少、短时间内密集生育以及非常年轻或年长女性生育减少有关。这些类型的生育也与五岁以下儿童高死亡率相关。以往研究关注的是避孕措施使用水平的变化以及这些高风险生育类型的平均变化。我们旨在预测当现代避孕措施的水平和方法发生变化时，某一特定国家的生育分布情况。
我们使用了来自207项覆盖71个国家的具有全国代表性的人口与健康调查中的完整生育史和现代避孕措施使用数据，根据生育顺序、上次生育间隔以及母亲生育时的年龄来描述每次调查中的生育分布情况。我们估计了现代避孕措施的普及率和方法组合与各类生育比例之间的生态关联。对这些汇总的横断面比例应用分层模型，以便对进行了多次调查的国家估计随机效应。我们利用这些结果预测在三种不同情景下扩大现代避孕措施使用与生育类型变化之间的关系。
我们观察到不同地区在避孕措施的绝对使用率、所用避孕方法类型以及生育类型分布方面存在显著差异。避孕方法组合是高风险生育比例的一个重要决定因素，尤其是对于生育间隔而言，但对于母亲年龄和胎次也是如此。现代避孕措施使用的增加尤其预示着胎次减少以及上次生育间隔更长的生育增多。然而，单纯避孕措施使用的增加与18岁以下女性生育减少或短间隔生育减少并无关联。
避孕措施的水平和类型都是决定计划生育对高风险生育分布变化影响的重要因素。对于随着现代避孕措施使用增加生育风险如何变化以及不同避孕方法的最佳预测，能够针对每个国家进行更细致入微的预测，并有助于更好地规划现代避孕措施的推广。
