Rinker School of Business, Palm Beach Atlantic University, Florida, USA.
Int Breastfeed J. 2022 Jul 7;17(1):51. doi: 10.1186/s13006-022-00479-4.
Both the consumption of breastmilk in infancy and a person's season of birth influences his or her health, educational, professional, and behavioral outcomes. Further, season of birth effects differ by sex. However, current research, for the most part, neglects to examine if season of birth and breastfeeding are related. This paper examines the impact of sex-based variations in season of birth on breastfeeding likelihood and duration in the U.S.
Using data from children born to female respondents of the National Longitudinal Survey of Youth 1979 (born between 1970 and 2012), this study examines with Probit, Negative Binomial, and Ordinary Least Squares (OLS) regressions if a child's season of birth and sex are correlated with breastfeeding incidence and duration. The breastfeeding incidence and duration data are self-reported by the mother.
Season of birth has a small but statistically significant impact on the incidence and duration of breastfeeding, which varies depending on the sex of the infant. Mothers giving birth to sons in the spring are 13.5% less likely to breastfeed than those giving birth to sons in the winter (with a p - value of 0.0269). Mothers with daughters born in the summer or fall (autumn) breastfeed slightly longer than mothers with daughters born in the spring. On average, mothers of summer-born daughters breastfeed 4.1% longer (with a 95% confidence interval of 0.3 - 7.8) and those with fall-born daughters 3.8% longer (with a 95% confidence interval of 0 - 7.5). Mothers giving birth to daughters in the spring are also significantly less likely to reach the breastfeeding six-week duration target (compared to fall and winter births) and the one-year duration target (compared to fall births).
These findings suggest that the costs and benefits of breastfeeding an infant vary with the season of birth and the sex of the child. This finding could explain some of the season of birth effects previously identified in the literature. Further, policymakers seeking to increase breastfeeding rates should consider the reduced breastfeeding rates and durations for children born in the spring.
婴儿时期母乳喂养和一个人的出生季节都会影响他或她的健康、教育、职业和行为结果。此外，出生季节的影响因性别而异。然而，目前的研究在很大程度上忽略了考察出生季节和母乳喂养之间是否存在关联。本文考察了美国基于性别的出生季节差异对母乳喂养可能性和持续时间的影响。
利用全国青年纵向调查 1979 年女性受访者的子女数据（出生于 1970 年至 2012 年之间），本研究使用 Probit、负二项式和普通最小二乘法（OLS）回归检验了孩子的出生季节和性别是否与母乳喂养的发生率和持续时间相关。母乳喂养的发生率和持续时间数据由母亲自行报告。
出生季节对母乳喂养的发生率和持续时间有很小但具有统计学意义的影响，其影响因婴儿的性别而异。春季分娩的母亲母乳喂养的可能性比冬季分娩的母亲低 13.5%（p 值为 0.0269）。夏季或秋季（秋季）出生的母亲哺乳时间略长于春季出生的母亲。平均而言，夏季出生的女儿的母亲母乳喂养时间长 4.1%（95%置信区间为 0.3-7.8），秋季出生的女儿母乳喂养时间长 3.8%（95%置信区间为 0-7.5）。春季分娩的母亲也不太可能达到母乳喂养六周的目标（与秋季和冬季分娩相比）和一年的目标（与秋季分娩相比）。
这些发现表明，母乳喂养婴儿的成本和收益因出生季节和孩子的性别而异。这一发现可以解释文献中之前确定的一些出生季节效应。此外，寻求提高母乳喂养率的政策制定者应考虑到春季出生的儿童母乳喂养率和持续时间降低的问题。
