1. Prevention CfDCa. 2002. Available from: https://www.cdc.gov/nchs/data/nvsr/nvsr51/nvsr51_01.pdf . Accessed 12/23/2017.
2. Prevention CfDCa. 2016. Available from: https://www.cdc.gov/nchs/data/databriefs/db232.pdf . Accessed 12/23/2017.
3. Prevention CfDCa. 2014. Available from: https://www.cdc.gov/nchs/data/databriefs/db152_table.pdf#1 . Accessed 12/23/2017.
4. mothers. SCTDSHadocooft. 2008. Available from: https://www12.statcan.gc.ca/census-recensement/index-eng.cfm?MM=1 . Accessed 31 Dec 2017.
5. Eurostat. Women in the EU gave birth to their first child at almost 29 years of age on average 2015. Available from: http://ec.europa.eu/eurostat/documents/2995521/6829228/3-13052015-CP-EN.pdf/7e9007fb-3ca9-445f-96eb-fd75d6792965 . Accessed 12/31/2017.