Synthetic oxytocin and breastfeeding: reasons for testing an hypothesis

Synthetic oxytocin is widely used in developed countries and in emerging countries as well. It is the most common medical intervention in childbirth. A great variety of side effects are plausible. There are in particular theoretical reasons to test the hypothesis that the increasing incidence of breastfeeding difficulties and the frequent earlier than desired cessation of breastfeeding are related to the use of synthetic oxytocin during labour. There have already been some studies that tend to support this hypothesis. Four hundred of the 7465 children born in 2006 at the Carlos Haya University Hospital (Malaga, Spain) were randomly selected. By interviewing the mothers, information about feeding type and duration was obtained in 2011 for 316 children. Among the 189 children who were born after labours induced or augmented with synthetic oxytocin, the odds ratio for bottle-feeding was 1.451 and the odds ratio for withdrawal at 3 months was 2.294. In addition, the Battelle Developmental Inventory was used to assess at age five 148 children (84 born with synthetic oxytocin): the odds ratio for neuropsychological development disorders after use of oxytocin was 1.46. The main limitation of such a preliminary study is that in the context of a tertiary Spanish hospital the possible effects of synthetic oxytocin on the quality and duration of breastfeeding cannot be easily dissociated from the effects of other components of pharmacological assistance during labour, particularly epidural fentanyl (a synthetic opioid analgesic). This comment is valid for all studies exploring the side effects of synthetic oxytocin in obstetric units of developed countries, including explorations through videotapes of the effects of synthetic oxytocin on primitive neonatal reflexes. It is also valid for studies exploring the side effects of obstetric analgesia without taking into account the use of synthetic oxytocin. This is why we underline the importance of conducting such studies in emerging countries (e.g. China and Brazil) where synthetic oxytocin is widely used while there are no epidural services. Studies of oxytocin given electively at the onset of third stage of labour (after the birth of the neonate) should help to interpret possible effects on the quality and duration of breastfeeding.