for a quantity of children to uphold the household economically, educational quality of the country rose during the same time period which meant that children held more a economical potential through educated labour means. The decline and equalling out of the gender gap in terms of place in the workforce meant that women were beginning in the 19th century to become a larger part of the workforce which also contributed to the birth rate decline. Improvements in public diets and nutritional quality increases, which are linked to biological factors such as a decline in lactation, have also been included as a potential factor in the decline of the fertility rate. Technological developments within the society also began to have an effect; contraceptive use become somewhat usable on a mass scale in the latter half of the 19th century due to technological developments in the production of rubber. Abortion, while illegal during the 19th century, was also used by women, however to what extent at the time is unknown. Cultural considerations such as decline in religious adherence (albeit little data on this matter during the 19th century) have also been considered as reasons. While these factors altogether are debated by demographers as to which were more important than each other, it is generally accepted that due to these factors overall, mothers could begin to invest more time and nurture 'quality' into their offspring rather than having a increased 'quantity' of children that were needed in the past for various such reasons, and that this development led to the decrease of the total fertility rate. By 1914, the birthrate sat at around 2.88 children per woman, however by 1918 had collapsed proportionally by almost 50% due to World War One and sank to 2.03 children. In the post-World War One period, while the birthrate of the country boomed at the very end of the war reaching a peak of 3.08 children in 1920, this began to endure a rapid decline and had slumped to historic lows by the 1930s, for the first time in the country's history falling below a replacement level fertility rate. This did not recover in-till the end of the Second World War in 1945. In the post-World War Two period, the fertility rate of the country boomed once again, bringing itself out of the below replacement level in the 1930s to levels not seen since the late 19th