Twin births are often construed as a natural experiment in the social and natural sciences on the premise that the occurrence of twins is quasi-random. We present new population-level evidence that challenges this premise. Using individual data for more than 18 million births (more than 500,000...

Twin births are often construed as a natural experiment in the social and natural sciences on the premise that their occurrence is quasi-random. We present new population-level evidence challenging this premise. Using data on about 18 million births in 72 countries, we find that maternal...

Twin births are often used to instrument fertility to address (negative) selection of women into fertility. However recent work shows positive selection of women into twin birth. Thus, while OLS estimates will tend to be downward biased, twin-IV estimates will tend to be upward biased. This is...

Religion Predicting Fertility Behaviour of Young Women in Contemporary GermanyReligion in contemporary Germany is marked by institutionalized outreach as well as increased pluralisation. Religion can thus play a decisive role in fertility behaviour, despite of secularizing tendencies. Religion...

It is a well known fact that economic development and distance to the equator are positively correlated variables in the world today. It is perhaps less well known that as recently as 1500 C.E. it was the other way around. The present paper provides a theory of why the 'latitude gradient'...

The paper analyzes 141 villages in Matlab, Bangladesh from 1974 to 1996, in which half the villages received from 1977 to 1996 a door-to-door outreach family planning and maternalchild health program. Village and individual data confirm a decline in fertility of about 15 percent in the program...

In this study we examine the passage of a reform to in-vitro fertilization (IVF) procedures in Sweden in 2003. Following publication of medical evidence showing that pregnancy success rates could be maintained using single rather than multiple embryo transfers, the single embryo transfer (SET)...

Despite the fact that Cesarean section (C-section) is the most commonly performed surgery in a number of industrialized countries, little is known about the long-term consequences for the mothers and children involved. In this study, I use a sample of high-risk births—namely, breech births, in...