Conception rates in under-18s
Rates of teenage pregnancy are often associated with poor educational achievement, poor physical and mental health, social isolation and poverty. The Public Health Outcomes Framework for England includes under-18 conceptions as a key measure for health inequalities and child poverty.
Under-18 conception rate per 1,000 population:
- Numerator: total conceptions in all women aged under 18
- Denominator: total female population aged 15 to 17.
Office for National Statistics (ONS) conception statistics are compiled by combining information from birth registrations and abortion notifications. Conception statistics include pregnancies that result in:
- one or more live or still births
- a legal abortion under the Abortion Act 1967.
Miscarriages and illegal abortions are not included. The date of conception is estimated using recorded gestation for abortions and stillbirths, and assuming 38 weeks gestation for live births. A woman’s age at conception is calculated as the number of complete years between her date of birth and the date she conceived.
The postcode of the woman’s address at time of birth or abortion is used to determine local authority/ward of residence at time of conception.
Only about 5% of under-18 conceptions are to girls aged 14 or under and to include younger age groups in the base population would produce misleading results. The 15 to 17 age group is effectively treated as the 'population at risk'.
ONS changed the methodology for estimating age at conception in 1997. Rates for 1987 to 1996 were revised to provide a comparable time series from 1987 onwards.