The PERSIAN birth cohort will be established in a number of centres for the PERSIAN adult birth cohort and will make use of already available infrastructures for these cohorts.

The pilot phase will be conducted in Isfahan and Yazd. A description of basic characteristics of these centres is presented inthe table below:

Recruitment of participants

We will select a combination of public and private healthcare providers in order to ensure they represent the ethnic and socioeconomic distribution in the underlying population. Pregnant women will be approached during their first pregnancy visit (at the end of first trimester) to these centres. Those consenting will be recruited if they have Iranian nationality, reside in the catchment area of the study centre, give birth in a reference hospital, and do not have any communication problem. The high rate of Caesarean section in Iran will provide PERSIAN birth cohort a unique opportunity to evaluate the short- and long-term health effects of Caesarean section. The child’s biological father will be also invited to participate in the study at the first pregnancy visit (directly if attending the visit and indirectly through letters if they are not attending the visit).