Single motherhood (yes, no) was obtained by questionnaire.
Immigrant status (yes or no) was obtained from the migration register.
Information on marital status (married or cohabiting vs. other) and night/shift work (yes vs. no) was obtained from the survey.
Additionally, information on the usage of oral corticosteroids (yes vs. no), statins (yes vs. no), and nonsteroidal anti-inflammatory drugs [NSAID (yes vs. no)] was obtained from the questionnaire, as well as the register of the nationwide Social Insurance Institute.
With the purpose of measuring bias as the tendency to respond "yes", a criterion index was obtained as: <img src="http://journals.plos.org/plosone/article/asset?id=info?doi/10.1371/journal.pone.0019221.e004.PNG" class= inline-graphic"/> In this manner, if FA is equal to the miss rate, c = inline-graphicgher or lower than the miss rate, c has negative or positive values respectively.
Resuscitation at birth (yes or no) – a measure of likely asphyxia – was obtained from birth records.
This score was obtained by summing all 3*14 coded evaluations: +2 when the raters correctly answered yes or no, +1 when they correctly answered probably yes or probably no, −1 when they incorrectly answered probably yes or probably no, and −2 when they incorrectly answered yes or no.
Self-reported physician-diagnosed mental illness (yes/no) was obtained.
Information on breastfeeding (yes/no) was obtained by postnatal questionnaires at the ages of 2, 6, and 12 months.
Information about age (continuous), sex (men/women), smoking habits (yes/no), affected vascular bed, state of anaemia (yes/no) and kidney failure (yes/no) was obtained from the patients' medical records.
