Fig. 1

The present study sample consisted of 233 twins of Caucasian origin (99% naturally conceived), born between 1969 and 1982, who participated in a prenatal programming study and had both placental telomere length and buccal swabs at adulthood available. We excluded 49 participants from our analysis (1) because DNA quality or concentration was insufficient (n = 21) or because triplicate measurements of telomere length were too variable (difference in quantification cycle more than 0.50) (n = 7), (2) because residential address was missing (n = 10), or (3) because information on smoking status during pregnancy was not filled out in the questionnaire (n = 11). The number of twins included in our analysis was 184