The Effect of Hormonal Contraceptives on Breast-milk Production and Infant Growth

Overview

The investigators propose a randomized clinical trial comparing the effect of 30 mcg ethinyl estradiol and LNG 150 combination oral contraceptive pills versus placebo, or LNG-IUS or Etonogestrel-releasing contraceptive implant (Implanon)on breast-milk intake and infant growth in exclusively breastfeeding mother-infant pairs. Mother-infant pairs will be randomly assigned either 30 microgram ethinyl estradiol combination oral contraceptive pills or identical placebo to start on post-partum day number 42 or Implanon implants or a LNG-IUS. All women will be offered nonhormonal contraceptives prior to randomization. The pairs will then be followed for four weeks. During this follow-up period, breast-milk intake will be quantified by administering deuterium oxide to exclusively breast-feeding mothers and measuring the enrichment of deuterium oxide in the saliva of their infants, otherwise known as the dose-to-mother method of Coward.17 Additionally, maternal and infant anthropometric measurements will be collected -- both as a value necessary to implement the breast-milk quantification method, as well as an outcome for analysis, and a daily diary will be kept by the women participating in the study that records infant feeds and diaper changes.

Women where allocated to an oral combined contraceptive pill, or placebo or a LNG-IUS or a etonogestrel-releasing subdermal contraceptive implant at day 42 after delivery. After the provision of the contraceptive method a 0.5 mg/kg of deuterium 99.99% according to the weight of the mother will be administer to all women. One sample of saliva from the mother and the child will be collected every day until 21 days after enrollment. Additionally, weight, height and size of the leg of each child will be measured at baseline, at the day 11 and at the day 21 after enrollment. Also, a diary with information of change of diapers and number of breastfeeding will be kept by each mother.