«Pregnancy Labor and Birth». Women's Health. 27. september 2010. Arkivert frå originalen 28. juli 2016. Henta 31. juli 2016. «The first stage begins with the onset of labor and ends when the cervix is fully opened. It is the longest stage of labor, usually lasting about 12 to 19 hours [...] The second stage involves pushing and delivery of your baby. It usually lasts 20 minutes to two hours.»
womenshealth.gov
«Pregnancy Labor and Birth». Women's Health. 27. september 2010. Arkivert frå originalen 28. juli 2016. Henta 31. juli 2016. «The first stage begins with the onset of labor and ends when the cervix is fully opened. It is the longest stage of labor, usually lasting about 12 to 19 hours [...] The second stage involves pushing and delivery of your baby. It usually lasts 20 minutes to two hours.»
