Pregnant women were recruited for the study using a variety of methods and were asked about use of medications, alcohol and tobacco, recreational drugs, herbals and other factors that could negatively affect birth outcome. The pilot study revealed that women would indeed volunteer to provide information on medication and lifestyle factors during pregnancy, with 2521 women enrolling from four countries over 8-18 months. The four countries include the United Kingdom (UK), The Netherlands (NL), Denmark (DK) and Poland (PL). Of those who enrolled in the PROTECT pregnancy study, only 2066 provided any data, with all but one providing data via internet.