Effect of breast feeding vs formula feeding on maternal health

Shahin Lockman presented findings from a prospective substudy from the Mashi PMTCT study. In this analysis, the investigators looked at maternal health outcomes by randomised infant feeding strategy.

Mothers were followed for up to five years post partum and received: clinical evaluation, CD4 at enrolment, delivery and then every 3-6 months; viral load at enrolment, delivery and the 6,12 and 24 months post partum and serum was taken 6 moths post partum from a random sample of 131 women (65 breast feeding/66 formula feeding) and tested for B12, vitamins A and E, selenium, albumin and hsCRP.

The primary endpoint was time to maternal death, AIDS or CD4 decline to <200cells/mm3. This was an intent-to-treat analysis using data from March 2001 to September 2007.

The investigators followed 1200 women for a median of 54 months. Baseline characteristics were similar in both arms: median CD4 was 366 and median viral load was 4.4 log10. In the formula feeding arm (n=602), 93% women exclusively formula fed. In the breastfeeding arm 95% initiated breastfeeding, only 18% exclusively breastfed for the full 5 months.

Overall, 372 (31.0%) of women reached an endpoint: 204/598 (34.1%) women in the breastfeeding arm and 168/602 (27.9%) in the formula feeding arm, p=0.08. Of the women experiencing an endpoint 26% vs 21% experienced CD4 decline; 6% vs 2% AIDS and 3% vs 3% death in the breastfeeding and formula feeding arms respectively.

The investigators found that, in multivariate analysis, formula feeding was not a predictor for the composite endpoint (adjusted hazard ratio, AHR 0.82, 95% CI, 0.67-1.01, p=0.07).

Factors associated with reaching an endpoint included baseline CD4 </=350 (AHR 0.54, 95% CI 0.43-0.68, p<0.01), viral load >/= median (AHR 1.42, 95% CI 1.14-1.77, p<0.01) and any education (AHR 0.59, 95% CI, 0.36-0.98, p=0.04).

They reported a trend towards faster progression to an endpoint among women in the breastfeeding vs formula feeding arm, which appeared to emerge more than 2 years after the end of the feeding strategy.

In the subgroup tested for micronutrients there was no difference in micronutrients or albumin between the two arms. Median hsCRP levels were higher in the women in the breastfeeding than the formula feeding arm, 2.28 vs 1.05 mg/L, p<0.01.

Lockman S et al. The Effect of Breast Feeding vs Formula Feeding on Maternal HIV Disease Progression, Mortality, and Micronutrient Levels in a 1200-Person Randomised Trial, Botswana. 16th CROI, Montreal, 2009. Abstract 176.
http://www.retroconference.org/2009/Abstracts/34385.htm