Contraception during breastfeeding must take two important factors into account: maternal contraceptive reliability, which matters for maintaining a proper interval between pregnancies, and the health of the newborn.
Oral contraception is the most effective and reliable method, but estrogens interfere with milk production, altering both its duration and quantity.
It is possible, however, to use a progestin-only pill (POP) containing desogestrel.
For women who do not want to, or find it difficult to, take a tablet every day, the subcutaneous implant may be considered: inserted under the skin of the arm by a specialist, it releases another progestin, etonogestrel, for three years.
The progesterone IUD can be used starting from the 6th week postpartum. Studies have documented a very small transfer of levonorgestrel (the hormone used in the coil): less than 0.1%. These studies showed no negative effect on the newborn's growth or health (Shaamash et al., Contraception 72, 2005).
Progesterone concentrations in maternal blood proved to be lower than those observed with the use of the progestin-only pill (desogestrel) or the subcutaneous implant (etonogestrel).
Fertilization is inhibited at several levels: changes in cervical mucus make it harder for sperm to travel upward and inhibit «capacitation», the process by which sperm acquire the ability to penetrate the egg cell during their journey through the female reproductive tract. The progesterone released into the uterine cavity suppresses the growth of the endometrium, the tissue responsible for receiving the embryo.
Uterine bleeding may be irregular in the first period after insertion, settling, in a significant percentage of women, into an absence of periods or light, infrequent bleeding.
The presence of progesterone in circulation can cause, in particularly sensitive women and especially in the early period, breast tenderness, skin problems, headaches and vaginal dryness, all generally mild.
It should be stressed that, here too, a personalized approach to choosing contraception is important: the doctor will assess any contraindications and guide the woman through the decision.