Parents want the best for their children. They want them to grow prosperous and happy, so a natural question is how can parents help them from the very conception. This problem is – probably much to surprise of many – continuously tackled by the economists. ASSA 2014 brought another two very interesting papers on fertility decision and how can they affect the future of our children.

The first paper provides an interesting example on how the environment conditions at the time of conception can have a strong impact on the child’s life. Bénédicte Apouey and Joshua Wilde (2013, available here) explored the role of heat waves at the time of birth in developing countries and found that they are correlated with higher educational attainment. In their preferred specifications, a 1 degree increase in temperature above the monthly average leads to an increase of more than 0.1 years of schooling. So, if you want to have better educated children, take a look at the thermometer before making any rush decisions.

Actually, it is not that simple. The effect of temperature is most likely to be indirect, through the education of the parents. As Apouey and Wilde indicate, better educated parents have a smaller decrease of sexual activity during heat waves, which implies a process of self-selection ("children of heat waves" are more likely to have educated parents than other kids). In fact, more direct variables such as health of the fetus had a negligible impact. While this study is still a work in progress, it might constitute a nice pick up line for the summer.

If by any chance you missed the last heat wave, which in Poland might be quite frequent, there is still hope for you and your child. Several studies, among them Hitoshi Shigeoka (2013), demonstrated that not only the weather at conception, but also the date of birth is relevant for the academic performance of the child. Specifically, children who were born after the schools cut-off dates (usually the first day of classes) tend to have better results in the PISA exams than those who were born before. This effect is partly due to the greater maturity of the child at the time they start the school and partly due to other socioeconomic factors, which are explored in greater detail in Shigeoka’s paper.

Shigeoka demonstrates that postponing the birth is a frequent strategy in Japan, where the cut-off date is on April 1^st. Japanese parents delay births by hours and even days in order to let their child be the oldest in their course. Obviously, this strategy is only viable for those parents who can afford having children longer at home (parents from richer houses), or who have access to childcare facilities. As the regression analysis shows, both factors are also correlated with the performance of the child at school. Can we afford to treat the date of birth as a purely random variable then?

What is the situation in Poland? In Poland, typically children whose birth date fall after September 1^st still begin school according to the year of birth (i.e. prior to completing 6/7 years of age). If the same mechanisms were at play as in Japan, we could see different frequencies of births around these dates. Sadly, Polish Household Budget Survey offers information on birthdays only for people over 16, so we cannot evaluate recent year; but, we can look at the dates of those already working as we do in the graph bellow.

Even though it is far from conclusive, the graph suggests a small fall before New Year’s Eve followed by a surge in January, 1^st.This tendency is specially marked among older people (60+), where the possibility of being born on that day doubles those of the second most popular day. An alternative explanation is a misreport of the date of birth within this group. Among the younger cohort, the first day of the year is the third most popular, behind June 15^th (probably related to Corpus Christi) and June 30^th. Both trends indicate that delaying birth might have been more common in the past than nowadays.