The Human Reproduction Programme of the World Health Organisation (HRP) produces a series of guidelines relating to sexual and reproductive health including two aiming to improve the quality of care in contraceptive provision; The Medical Eligibility for Contraceptive use (which gives guidance on who can use specific contraceptive methods) and the Selected Practice Recommendations for Contraceptive Use (how to use the available methods safely and effectively). Both are available on the HRP website [1] and both have been updated in 2008.

The Guideline Development Group has struggled with giving guidance on use of hormonal contraceptives by women who are breastfeeding. Since there is good evidence that exogenous estrogens reduce the quantity of breast milk the guideline recommends that all combined hormonal contraceptives (the pill, patch, ring and combined injectable) should not be used at all during the first 6 weeks postpartum and can only be used if no other method is acceptable or available from 6 weeks to 6 months after childbirth. While there is no evidence that progestogen-only methods impair lactation, some group members have suggested that the ingestion of progestins in breast milk may interfere with the development of the brain and liver of neonates and infants. For this reason the guideline also recommends that progestin-only methods are avoided during the first 6 weeks post partum.

Many members of the group responsible for updating the guidelines are uncomfortable with limiting the use of progestin only contraceptives (POC) because the evidence for any harm is extremely limited and of poor quality. There is also very limited research evidence for their being no harm. However hundreds of thousands (perhaps millions) of women in both developed and developing countries have used POC in the early post partum period - in some countries high dose depot injections (Depo Provera(registered trademark) and Norethisterone-enanthate) have been routinely given on the day of delivery and there is no evidence for any serious consequences for neonatal health. An expert group was convened in late October 2008 to consider whether there is any compelling evidence for an effect of progestins in breast milk on development of the brain or liver of neonates and infants. The experts included, among others, a paediatrician and two basic scientists who have done a lot of research on the effect of estrogen and progestogen on the brain - but in rats! While the conclusion of the meeting was that there was no compelling evidence of harm, the experts pointed out that they could not exclude a subtle effect of contraceptive progestogens on behaviour (such as ADHD for example), cognition or even sexuality in later years. So we are stuck with not recommending POC for women during the first 6 weeks postpartum (and logic would ask why, if there could be a harmful effect, is it acceptable to use these methods after 6 weeks when the baby's brain is still developing rapidly).

Of course the chance of a breastfeeding woman conceiving before 6 weeks after delivery is remote. However in many developing countries it is difficult for women to negotiate condom use with their partners, intrauterine devices are rarely available and diaphragms are not used so this leaves not much else for effectively preventing pregnancy and short inter-birth intervals. The long-acting methods of POC give 3-5 years protection from pregnancy (or longer) but the only opportunity to start these methods, since they require a skilled health professional, is missed if the newly delivered mother leaves the place where she had her baby and does not have access to a skilled provider thereafter.

We are aware that the ALSPAC cohort of mothers and infants has collected data on a wide range of outcomes and wonder whether it may be possible to use your data to investigate the effects of contraceptive progestogens ingested in breast milk on infants and children. Breastfeeding women in the UK commonly start using the progestogen-only pill at 28 days after delivery and some who use Depo Provera(registered trademark) may start even earlier.

We are unsure as to whether ALSPAC has collected data on postpartum contraceptive use which is of sufficient detail to cast light on the possible effects on breastfeeding babies and infants (i.e. contraceptive method used and start (and stop) dates. If not there is no point in pursuing this further. If data are sufficiently detailed we would be interested in linking contraceptive use during breastfeeding with any subsequent pathology in the offspring.

1. http://www.who.int/reproductive-health/publications/family_planning.html)