Lactation may lower risk of stroke among women, finds JAMA study

China: Lactation was significantly associated with a lower risk of stroke, especially ischemic stroke, emphasizing the importance of promoting breastfeeding as a targeted prevention strategy of stroke, says an article published in the Journal of American Medical Association.

Previous research has found a link between breastfeeding and a lower risk of cardiovascular disease. Distinct pathogenic mechanisms produce different stroke subtypes; however, the connections of breastfeeding length with different stroke subtypes are less well established. As a result, Ziyang Ren and colleagues undertook this study to investigate the correlations of breastfeeding length with stroke and its subtypes in parous postmenopausal women. 

At the outset of this population-based prospective cohort research, parous postmenopausal women aged 45 to 79 years old were included in the China Kadoorie Biobank (CKB) project (2004-2008). Lactation length was calculated as a lifetime average, per kid, and for the first child. During the follow-up period, new-onset stroke and its subtypes (ischemic stroke, intracerebral hemorrhage [ICH], and subarachnoid hemorrhage [SAH]) were examined using illness registries and national health insurance claim databases (2008-2015). From June to December 2021, data were evaluated. Women with a lifetime lactation duration, mean per child, and for the first child were included. Total stroke, ischemic stroke, ICH, and SAH were the primary outcomes. The adjusted hazard ratios (aHRs) with 95 percent CIs for stroke and subtypes were calculated using multivariable Cox regression.

The key findings are as follow:

1. 15 721 strokes occurred among 129 511 parous postmenopausal women who had no prior stroke at baseline, with a median (IQR) lifetime lactation duration of 42.0 (24.0-70.0) months among 13 427 women who had an ischemic stroke, 54.0 (36.0-84.0) months among 2567 women who had ICH, and 36.0 (24.0-64.5) months among 284 women who had SAH.

2. In comparison to parous postmenopausal women who had never lactated, those who had lactated for at least 7 months had a decreased risk of ischemic stroke and ICH.

3. In the case of SAH, however, such relationships were detected only in women who had a lifetime breastfeeding duration of more than 24 months.

4. Furthermore, women with a mean breastfeeding length per child or a first-child lactation duration of 7 months or longer were less likely to suffer a stroke and its subtypes.

In conclusion, according to the 2019 National Survey on Factors Influencing Breastfeeding, China's exclusive breastfeeding rate for babies under 6 months is 29.2 percent, much lower than the worldwide mean of 43 percent in low-income countries and 37 percent in middle-income countries. These findings highlight the significance of lactation and urge policymakers and the general public to prioritize breastfeeding.

Reference:

Ren Z, Yi Q, Hou L, et al. Lactation Duration and the Risk of Subtypes of Stroke Among Parous Postmenopausal Women From the China Kadoorie Biobank. JAMA Netw Open. 2022;5(2):e220437. doi:10.1001/jamanetworkopen.2022.0437