Characteristics of the original ELEMENT cohort participants
| Mean±SD or % | ||||
| Cohort 1 | Cohort 2 | Cohort 3 | ||
| 2A | 2B | |||
| Maternal characteristics | n=639 | n=327 | n=533 | n=670 |
| Age at enrolment (years) | 24.6±5.1 | 26.9±5.3 | 25.2±5.1 | 26.4±5.5 |
| Gestational age at enrolment (weeks) | 39.1±1.6 | 15.4±5.9 | 38.9±1.3 | 13.1±2.1 |
| Marital status (%) | ||||
| Married or cohabiting | 91.10 | 91.10 | 93.30 | 88.50 |
| Single | 8.90 | 8.90 | 6.70 | 11.50 |
| Maternal education (years) | 9.34±3.1 | 10.75±3.2 | 10.84±3.0 | 10.7±2.9 |
| Parity (including index birth) (%) | ||||
| 0 | 0 | 1.50 | 0 | 0 |
| 1-2 | 73.60 | 70.90 | 78.40 | 70.40 |
| ≥3 | 26.40 | 27.50 | 21.60 | 29.60 |
| Smoked during pregnancy (%) | 4.30 | 4.00 | 9.50 | 2.20 |
| Calcium treatment (%, N) | 47.00 | N/A | N/A | 50.00 |
| Delivery method (%) | ||||
| Vaginal | 77.30 | 46.20 | 91.10 | 50.70 |
| Forceps | 1.70 | 3.50 | 3.40 | 1.10 |
| C-section | 19.70 | 40.00 | 5.00 | 21.30 |
| Missing | 1.30 | 12.80 | 0.40 | 26.90 |
| Offspring characteristics at delivery | n=632 | n=253 | n=433 | n=393 |
| Sex (%) | ||||
| Male | 54.50 | 51.90 | 54.10 | 49.40 |
| Female | 45.50 | 48.10 | 45.90 | 50.60 |
| Gestational age at delivery (weeks) | 39.2±1.5 | 38.6±1.9 | 39.0±1.2 | 38.6±1.7 |
| Birth weight (g) | 3153±474 | 3102±531 | 3130±484 | 3131±484 |
ELEMENT, Early Life Exposure in Mexico to ENvironmental Toxicants.