The overall data indicate that the LNG levels transferred to fully breast-fed infants through breast milk from Norplant users significantly modified their TSH levels.

GnRH agonists have advantages over steroids for hormonal contraception during the postpartum period in breastfeeding women. Symptoms of hypoestrogenism were not reported any time in either the controls or the treated groups, as estrone levels were not suppressed to menopausal values. Once-daily administration of GnRH agonist could be a reliable, acceptable and safe contraceptive method during the postpartum period in breastfeeding women. More information is required to establish GnRH analog contraceptive efficacy.

The effects of four low doses of synthetic steroids, administered orally and starting on day 8 (group I) or on day 10 of the menstrual cycle (group II), upon LH surge, ovarian steroidogenesis, follicular maturation and menstrual cycles were studied in 10 eumenorrheic women. The results revealed that the day before the LH surge, the highest level of estrone-3-glucuronide was observed in both groups. Twenty-four hours after the last dose, the maximum urinary LH levels were recorded in groups I (day 11), and II (day 13). Pregnanediol-3 alpha glucuronide remained low during the study in group I, whereas in group II a gradual rise of this hormone starting on day 13 was registered and the highest level was found at day 21 of the menstrual cycle. Follicular maturation and ovulation were observed only in women from group II. Short and normal length cycles were recorded in groups I and II, respectively. In summary, low doses of exogenous synthetic steroids administered on day 8, but not on day 10 of the cycle, inhibit follicular maturation and ovulation.