In 2009 a study of 500,000 low-risk planned home and hospital births in the UK, where midwives have a strong licensing requirement, was reported in the "British Journal of Obstetrics and Gynaecology". The study concluded that for low-risk women there was no increase in perinatal mortality, provided that the midwives were well-trained and there was easy and quick access to hospitals. Further, the study noted there was evidence that "low risk women with a planned home birth are less likely to experience referral to secondary care and subsequent obstetric interventions than those with a planned hospital birth." The study has been criticised on several grounds, including that some data might be missing and that the findings may not be representative of other populations.