Maternal High Blood Pressure and Breastfeeding
by Anne Eglash MD, IBCLC, FABM
High blood pressure is one of the most important illnesses that leads to gradual ‘end organ’ destruction as an individual grows older. An elevated blood pressure causes damage to blood vessels, and the body tries to patch this damage with cholesterol laden plaque. The brain, heart and kidneys become damaged over the course of time from uncontrolled high blood pressure, leading to ‘old age’ illnesses such as dementia, heart disease, chronic kidney disease, and aneurysms of various arteries.
Controlling high blood pressure is therefore one of the most important public health measures for a healthy and enjoyable quality of life through the senior years.
A group of researchers evaluated all existing evidence to determine the strength of the impact of breastfeeding on high blood pressure in women. They found 19 high quality articles that fit the criteria to evaluate this association. The articles included populations from Asia, Northern Europe and the USA. Four of the 19 studies followed women for less than 6 months postpartum, and 15 studies followed women for 3 to 35 years postpartum.
- The protective effect of breastfeeding on high blood pressure occurs after 1 month of lactation, and not before.
- Studies with a longer duration of follow up are more likely to show an association between breastfeeding and normal blood pressure.
- The main reason why breastfeeding women have lower blood pressure is because they lose more weight postpartum than women who didn’t breastfeed.
- The effect of breastfeeding on high blood pressure is not seen after menopause.
See the Answer
Hypertension is relatively common in pregnancy, and pregnancy may unmask hypertension among women who are predisposed to it. Lactation may be a means through which to mitigate pregnancy-related vascular risk. The impact of lactation on maternal blood pressure, and the duration of any effect, remains unclear. This study aimed at systematically reviewing the literature evaluating the impact of lactation on the development of hypertension.
Materials & Methods:
We searched PubMed, including EMBASE and MEDLINE, for studies that reported on the association between breastfeeding and maternal risk of hypertension that were published in a peer-reviewed source. The quality of the studies included was assessed by using the Newcastle-Ottawa Scale.
Nineteen studies met all inclusion criteria for this review. Of the four studies with short-term follow-up, 50% showed a protective association. The fifteen studies with longer-term follow-up were stratified by outcome assessed. Sixty-seven percent of the studies that evaluated for elevated blood pressure and 100% of the studies evaluating for an outcome of hypertension showed a protective association. The minimum duration of lactation associated with a benefit was 1 month. This association was demonstrated in follow-up periods as long as two to three decades. Studies that showed a protective association had overall higher quality ratings.
Lactation is associated with a beneficial effect on maternal blood pressure that persists for decades. These results add to the growing body of literature demonstrating the protective association of lactation on maternal cardiovascular risk. Providers may incorporate the decreased risk of hypertension into their counseling on the maternal benefits of lactation.
It is no coincidence that this systematic review of 19 studies showed a strong correlation between breastfeeding and lower risk of maternal high blood pressure. This finding is consistent with other studies that have shown that breastfeeding protects from vascular diseases associated with high blood pressure, including strokes, calcification in the aorta, and heart attacks.
We don’t know the exact physiologic reason why breastfeeding protects from high blood pressure. Some researchers have hypothesized that it has to do with losing weight postpartum, but the effect on blood pressure is seen after breastfeeding for just 1 month, which is before women have lost much weight.
Since vascular diseases are the most common causes of morbidity and mortality among women as they age, all pregnant women deserve to know that breastfeeding for at least 1 month will help decrease their future risk of vascular disease. There is no evidence that this effect is gone after menopause.
Hopefully in the future we will have better quality data to understand the strength of the relationship between breastfeeding duration beyond 1 month and risk of vascular disease.