Combined Hormonal Versus Progestin Only Contraception During Lactation

Objective: To determine and compare the effect of low dose estrogen combined hormonal contraceptives and progestin-only contraceptives on lactation.

The subjects will be drawn from a healthy obstetric population in each center, where possible preliminary contact during antenatal period. At the postpartum visit, subjects that express their wish for a hormonal contraceptive method will be offered enrollment. After obtaining an informed consent the participants will be allocated according to their free wish to either receive a combined preparation containing 0.02 mg ethylestradiol and 0.15 mg desogestrel (Mercilon, Organon) or a progestin only pill containing 0.075 mg desogestrel (Cerazette, Organon). Demographic, habits and perinatal data will be collected and stored to analysis.

Frequency and methods of observation: All women will be followed at 6 (baseline), 9 and 12 weeks post - partum. Instruction will be given as to recording information on intercurrent disease, frequency of nursing and use of complementary formula supplements. Maternal BMI calculation ( weight/height2) will be obtained at first visit.

The objective is to compare the capacity of the breast to secrete milk under standard conditions and evaluate the influence of different hormonal contraception means. Thus samples will be collected at 6 weeks (enrollment) and the 9 and 12 weeks visits. An Egnell pump will be used for a maximum of 20 minutes form from both breasts, simulating a regular breast feeding. A total of 10 ml aliquot will be taken for composition analysis and the rest will be offered to the infant. The milk volume/feeding will be estimated and expressed in ml/feeding and multiplied by the number of feedings reported.

Outcome variables: Milk volume, infant growth at each visit and biochemical markers of milk analysis : lipid, casein and carbohydrate content