Dose-Response Relationships between Breastfeeding and Postpartum Weight Retention Differ by Pre-Pregnancy Body-Mass Index in Taiwanese Women

Abstract

Postpartum weight retention (PWR) is a risk factor for future obesity. The role of breastfeeding in reducing PWR is not fully understood. We examined the relationship between PWR and the duration of exclusive/partial breastfeeding in 52,367 postpartum women from 2012-2016 Taiwan national breastfeeding surveys. The women were interviewed at 7-14 months postpartum. Non-linear models were fit to examine the association between PWR and breastfeeding duration. PWR adjusted means and 95% confidence intervals were plotted and compared for the duration of exclusive/partial breastfeeding in the total sample and between pre-pregnancy body-mass index (BMI) groups (underweight, normal, overweight, and obese). Women who breastfed exclusively for >30 days showed significantly lower PWR than those who did not breastfeed and those who breastfed partially for the same duration, thereafter each additional duration of 30 days being associated with an average of 0.1-0.2 kg less PWR. Women who breastfed partially for 120 days showed lower PWR than those who did not or those who ceased to breastfeed, thereafter each additional duration of 30 days being associated with an average of 0.1 kg less PWR. Duration of breastfeeding needed to achieve significantly less PWR differed between pre-pregnancy BMI groups, but the effect of exclusive breastfeeding appeared earlier in the normal weight group. Women with obesity who breastfed exclusively for >30 or partially for >180 days, had lower PWR than non-obese groups. The observed dose-response relationship between breastfeeding duration and PWR supports the "every feeding matters" approach in breastfeeding promotion. The larger effect of exclusive and partial breastfeeding on PWR in women with obesity may draw special attention of breastfeeding promotion.

Keywords: Taiwan; exclusive breastfeeding; obesity; pre-pregnancy body mass index.

Figure 1

Adjusted means and 95% confidence intervals of postpartum weight retention and duration of breastfeeding in Taiwanese women (N = 52,367). Notes: (1) postpartum weight retention was assessed at 7–14 months postpartum; (2) X-axis represents duration of breastfeeding in days postpartum; (3) each time point on the same curve represents different women; (4) exclusively breastfeeding women that started adding food, liquids or formula are represented at a later time point on the curve for partial breastfeeding; (5) women that ceased breastfeeding completely are represented at a later time point on the curve for no breastfeeding; (6) sample sizes do not sum up to the total because of the cross-sectional design of the study.

Figure 2

Adjusted means and 95% confidence intervals of postpartum weight retention and duration of breastfeeding in Taiwanese women by pre-pregnancy BMI (N = 52,367): (A). underweight (n = 8911), (B). normal (n = 34,927), (C). overweight (n = 5419), (D). obese (n = 3110). Notes: (1) postpartum weight retention was assessed at 7–14 months postpartum; (2) X-axis represents duration of breastfeeding in days postpartum; (3) each time point on the same curve represents different women; (4) exclusively breastfeeding women that started adding food, liquids, or formula are represented at a later time point on the curve for partial breastfeeding; (5) sample sizes do not sum up to the total because of the cross-sectional design of the study; (6) sample sizes for each time point are available in the supplementary materials (Supplementary Table S2); (7) weight status categorized by BMI cutoffs for Taiwanese population—18.5, 24 and 27 kg/m² (Taiwan Health Promotion Administration. (2018). BMI classification (in Chinese). Retrieved from http://health99.hpa.gov.tw/OnlinkHealth/Onlink_BMI.aspx).

Figure 3

Postpartum weight retention and duration of breastfeeding in Taiwanese women by pre-pregnancy BMI (N = 52,367): (A). exclusive breastfeeding; (B). partial breastfeeding. Notes: (1) postpartum weight retention was assessed at 7–14 months postpartum; (2) X-axis represents duration of breastfeeding in days postpartum; (3) each time point on the same curve represents different women due to the cross-sectional design of the study; (4) sample sizes for each time point are available in the supplementary materials (Tables S2 and S3); (5) weight status was categorized by BMI cutoffs for Taiwanese population—18.5, 24, and 27 kg/m² (Taiwan Health Promotion Administration. (2018). BMI classification (in Chinese). Retrieved from http://health99.hpa.gov.tw/OnlinkHealth/Onlink_BMI.aspx).