Birth rate is defined as the number of live births per 1000 of the population per year, one factor that has had an influence on birth rates and family size since 1900 is the fertility rate. The total fertility rate (TFR) in England and Wales saw a steady decline during the 1990s, to a low of 1.63 in 2001 and then gradually increased between 2001 and 2008. From 2008 the TFR has remained relatively stable, shifting between 1.90 and 1.94 children per woman and peaking in 2010, however it is still lower than the peak of 2.95 children per women during the 1960’s during ‘baby bloom’ this emphasises more women are remaining childless than in the past due to the changing role of a women and also women are postponing having children: the average age for giving birth is now 29.6 and fertility rates for women in their 30’s to 40’s are now on the increase, older women may be less fertile and fewer fertile years remaining and produce fewer children.
Interlinking with the factor of changing roles of women, there were major changes back in the 2oth that gave women the right to have more opportunities in their life; legal equality with men -the right to vote, increased educational opportunities- it has now been shown that girls are doing better than boys. Women with stable and high paid jobs are more likely to have less committing relationships as they are less likely to settle down until their late 30’s and start a family later on in life decreasing birth rate. Changes in attitudes to family life and women’s role, women in the 21st century are free to have a day job, she doesn’t have to be a stay at home wife as the women becomes more active in her day life creating a dual earner relationship this factor may decrease family size because a couple may prefer the freedom that consist within their relationship instead of the responsibility, on the other hand couples who earn more can afford to look after a large family. Staceys findings in 1998 showed that women were the main cause for change in the family but also many started to reject the housewife role to be able to achieve more in their life the conclusions from her findings showed that women started to increase the rate of divorce and get remarried, into a life that suited them this had a knock on effect, Child birth increased as women started having children with their new husbands.
Access to contraception and abortion, giving women control over their fertility- This factor shows a major decrease in birth rate, women become more free to have sex without getting pregnant and lose the influence of religion but into society, Catholics argues against contraception and sex before marriage more people are having sex for the pleasure and less for the reproduction. Women are allowed to delay their choice in having a child. In 2006 one in five women aged 45 was childless, double the number of 20 years earlier.
Additionally another factor to effect birth rates and family size is the infant mortality rate, measures the number of infants who die before their first birthday per thousand babies born alive per year. More parents have more children to replace those that are lost, thereby increasing the birth rate by contrast if infants survive, parents have fewer children- In 1900’s the IMR for the UK was 154 (15% of babies died within their first year) however the statics are much higher than those in less developed countries as a summary to this disease is one of the factors that effects birth rates. Improved housing and better sanitation, such as flush toilets and clean drinking water, reduced infectious disease. Young children are much susceptible to infections due to their less developed immune system, helping reduce diseases can allow a family to have larger families knowing each child will live; especially in traditional families and culture they preference big families playing an increase on family size.

Overall this shows multiple factors that may cause a increase or decrease in family size and birth rate, the factors influence each other and recently there was figures published showing an increase of family size, There were 7.7 million families with dependent children in the UK in 2012, 1 in 7 of which had three or more dependent children.