5. Age at conception

Between 2010 and 2011 conception rates in 2011 increased for women aged 30 years and over, stayed the same for women aged 25–29 and decreased for women aged under 25 years. The largest percentage increase in conception rates occurred among women aged 40 and over (3.7%). Smaller increases in conception rates were recorded among women aged 30–34 and 35–39 rising by 1.2% and 2.1% respectively. Conception rates for women aged under 20 and 20–24 have decreased by 7.6% and 2.5% respectively.

Figure 2: Relative changes in age-specific conception rates, 1990–2011 England and Wales Source: Office for National Statistics Download this chart Figure 2: Relative changes in age-specific conception rates, 1990–2011 Image .csv .xls

The conception rate for women aged 40 and over has more than doubled since 1990 (Figure 2) from 6.6 to 13.9 conceptions per thousand women. The number of women in this age group conceiving has risen from 12,032 in 1990 to 28,747 in 2011. For women aged 40 and over, the percentage of conceptions leading to abortion fell from 43% in 1990 to 28% in 2011. Compared with 2010, the number of conceptions to women aged 40 and over has increased by 3.0%, but the percentage of conceptions leading to abortion decreased by 0.3 percentage points. Reasons for an increased number of women aged 40 and over conceiving include increased participation in higher education; delayed marriage and partnership formation (ONS 2012); the desire to establish a career, get on the housing ladder and ensure financial stability before starting a family ( Jefferies, 2008 (297 Kb Pdf) ; Ní Bhrolcháin, 2012).

The conception rate for women aged 35–39 continued to rise, from 61.5 conceptions per thousand women in 2010 to 62.8 in 2011, a rise of 2.1%. The number of conceptions to this age group fell by 1.4%, indicating that this rise was due to the size of the female population of childbearing age decreasing by 3.4% between 2010 and 2011.

Women aged 30–34 had the lowest proportion of conceptions leading to abortion at 13% in 2011. This is the same as 2010, when this age group also experienced the lowest proportion of conceptions leading to abortion. The conception rate continued to rise for this age group, reaching 124.9 conceptions per thousand women in 2011, compared with 89.7 in 1990 and 123.4 in 2010. The 30–34 age group is the youngest age group in which conception rates have risen almost continuously since 1990 and the rise may also be associated with the reasons outlined above.

Conceptions to women aged 25–29 have remained fairly stable, with the conception rate unchanged at 129.3 between 2010 and 2011. The conception rate for this age group declined between 1990 and 2001 when it reached 114.2 conceptions per thousand women, a fall of 17% before gradually rising. The conception rate for women aged 25–29 is now 6.3% below the 1990 level of 138.0 conceptions per thousand women aged 25–29.

Conceptions to women aged 20–24 have followed a similar pattern to the 25–29 age group, although the conception rate for this age group fell in 2011 (a 2.5% decrease). The conception rate has increased since 2001 and the conception rate for women aged 20–24 in 2011 is 14% below the 1990 level of 124.0 conceptions per thousand women.

The conception rate for women aged under 20 fell by 7.6% to 48.9 conceptions per thousand women aged 15–19 in 2011 (from 52.9 in 2010). This continues the overall downward trend in the conception rate for women aged under 20 since 2007 from 61.4 conceptions per thousand women. In 2011 conceptions to women aged under 18 accounted for 37% of all conceptions to women aged under 20, this compares with 38% in 2010.

In 2011 there were 31,051 conceptions to women aged under 18 compared with 34,633 in 2010, a decrease of 10%. This is the lowest number of conceptions in this age group since 1969. Nearly half (49%) of all conceptions to women aged under 18 in 2011 led to an abortion, this figure has remained relatively unchanged since 2006.

The under 18 conception rate for England and Wales was 30.9 conceptions per thousand women aged 15–17 in 2011 compared with 34.3 in 2010, a decrease of 9.9%. This is the lowest estimated under 18 conception rate since comparable conception statistics were first produced in 1969. This fall in the conception rate can be attributed to a 11.7% fall in the conception rate leading to abortion and a 8.1% fall in the rate of conceptions leading to a maternity. Figures for 2011 continue the overall downward trend in the conception rate for women aged under 18 since 1998 when there were 47.1 per thousand women aged 15–17, despite slight increases in 2002 and 2007. Since 1998 the conception rate for women aged under 18 has decreased by 34%.

Figure 3: Under 18 conception rate, 1975–2011 England and Wales Source: Office for National Statistics Notes: Rates have been calculated using the latest population estimates. Rates for 2002-2010 have been calculated using the revised mid-year population estimates which take account of the 2011 Census. 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. The conception rates for 1975 to 1986 are not directly comparable as they have been calculated using the previous methodology for estimating age at conception. See background note 3 for more information. Download this image Figure 3: Under 18 conception rate, 1975–2011 .png .xls

The number of conceptions to girls aged under 16 decreased by 10% from 6,674 in 2010 to 5,991 in 2011. A similar decline can also be seen in the conception rate for girls aged under 16. In 2011 there were 6.1 conceptions per thousand girls aged 13–15 compared with 6.8 in 2010, a decrease of 10%. This fall in the conception rate consists of a 12% fall in the rate of conceptions leading to abortion and a 4.0% fall in the rate of conceptions leading to a maternity. The percentage of conceptions leading to abortion for this age group has also fallen from 63% in 2010 to 60% in 2011.

Overall the under 16 conception rate has decreased over the last decade from 8.0 conceptions per thousand girls aged 13–15 in 2001 to 6.1 in 2011 despite small rises in some years. The under 16 conception rate is the lowest since 1969, the first year for which we have comparable data, when a rate of 6.9 conceptions per thousand girls aged 13–15 was recorded. Nearly three-quarters (71%) of under 16 conceptions in 2011 were to girls aged 15.

There are a number of factors which could explain the recent reduction in teenage conceptions, including: