Original research articleA comparative study of the levonorgestrel-releasing intrauterine system Mirena® versus the Copper T380A intrauterine device during lactation: breast-feeding performance, infant growth and infant development
Introduction
Each year, more than 100 million women make decisions about beginning contraception after childbirth. Choices for contraception may be limited for lactating women due to concerns about hormonal effects on quality and quantity of milk, passage of hormones to infants and infant growth [1]. According to the data of a recent Egyptian demographic and health survey, approximately 80% of Egyptian women breast-fed for at least 6 months and 40% breast-fed for up to18 months. Thirty-six percent of mothers with children younger than 6 months were exclusively breast-feeding and amenorrheic, but only 4% reported relying on breast-feeding for family planning [2].
A number of progestogen-only contraceptives have been shown not to influence breast-feeding or the growth and development of breast-fed infants. These methods include the following: progestogen-only pills (POPs), depot-medroxyprogesterone acetate (DMPA) injectables, norethisterone enanthate (NET-EN) injectables and subdermal contraceptive implants releasing levonorgestrel (LNG; Norplant®) [3], [4]. However, it is suggested that implants that release orally inactive progestin (e.g., nestorone and elcometrine) represent an advantage since infants should be free of steroidal effects [5].
LNG-releasing intrauterine systems (LNG-IUSs) release LNG locally in the endometrium at very high concentrations that are more than 1000-fold greater than serum levels [6]; atrophic changes in the endometrium markedly limit endometrial LNG uptake [7]. Only 0.1% of the serum dose of LNG can be transferred via milk to nursing infants [8]. LNG-IUSs are long-acting progestogen-only contraceptives, rapidly reversible and deliver the lowest daily dose of hormones (10–30 μg/24 h) [9], [10]. Actually, the plasma concentrations achieved by LNG-IUS are lower than those seen with Norplant® and LNG minipills [11], [12], [13].
In his pioneer study, Heikkilä [10] tested the safety of LNG-IUS releasing 10 and 30 μg per 24 h inserted 6 weeks postpartum on breast-feeding duration, infant growth and infant development. He concluded that LNG measured in milk is very low and no harmful effects on breast-feeding or infant growth were observed. However, to date, evidence from randomized controlled trials on the effect of hormonal contraceptives during lactation is limited and inadequate to make clear recommendations. More properly conducted randomized controlled trials of adequate size are still needed to address this question [1].
The present study was designed to evaluate the possible effects of an LNG-IUS (Mirena®) that releases 20 μg/day on breast-feeding performance and infant growth and development during the first postpartum year.
Section snippets
Study design and subject selection
This is a prospective, controlled and randomized trial of LNG-20 μg IUS (Mirena®) and the Copper T380A intrauterine device (Cu T380A IUD). It was conducted at the Department of Obstetrics and Gynecology, Assiut University Hospital, Egypt. During the period June 2001–June 2003, a total of 320 exclusively breast-feeding women requesting contraception during the second month postpartum was enrolled. All women had given birth to healthy term babies without any health problem and had no
Admission characteristics and continuation rates
The salient characteristics of participants and their infants at the time of admission are presented in Table 1, Table 2; they were comparable in both groups without any significant difference. Table 3 gives the cumulative net continuation rates of IUD use in both groups; they were nearly similar in both groups with no statistically significant differences (89.3 for LNG-20 μg IUS vs. 90.9 for Cu T380A IUD; per 100 women at the end of the first postpartum year).
Breast-feeding performance
Table 4 shows breast-feeding
Discussion
This study was carried out to answer the question of whether the use of Mirena® during the first year of lactation would affect breast-feeding performance, infant growth or infant development. The continuation rates for IUDs were satisfactory at the end of the first postpartum year and were nearly similar in both groups (89.3 for LNG-20 μg IUS and 90.9 for Cu T380A IUD). The Family Health International states that the continuation rates in developing countries among women using various types of
Acknowledgment
The LNG-20 μg IUSs (Mirena®) were kindly supplied by Schering.
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