Table I.
Characteristics of participating children and parents of the Groningen ART cohort study groups.
| Characteristics | OS-IVF/ICSI | MNC-IVF/ICSI | Sub-NC |
|---|---|---|---|
| n = 57 | n = 46 | n = 66 | |
| Child characteristics | |||
| Male gender, n (%) | 32 (56) | 22 (48) | 33 (50) |
| First born, n (%) | 38 (67) | 33 (72) | 39 (59) |
| Age at examination in months, median (range) | 110.4 (108.5–126.5) | 110.3 (108.2–131.8) | 109.9 (100.7–119.9) |
| Fertility parameters | |||
| TTP in yearsa, median (range) | 4.0 (0.1–13.3)*** | 3.8 (0.1–7.5)** | 2.0 (0.1–11.3)***/** |
| ICSI, n (%) | 37 (65) | 21 (46) | n.a. |
| Gestational characteristics | |||
| Smoking during pregnancy, n (%) | 6 (11) | 5 (11) | 6 (9) |
| Alcohol use during pregnancy, n (%) | 3 (5) | 0 (0) | 2 (3) |
| Use of folic acid during pregnancyb, n (%) | 50 (93) | 46 (100)* | 57 (86)* |
| Vanishing twins, n (%) | 6 (11)** | 1 (2) | 0 (0)** |
| Birth characteristics | |||
| Gestational age in weeks, median (range) | 39.4 (33.4–42.3)* | 39.9 (34.6–42.6) | 40.1 (30.1–42.6)* |
| Preterm birth (<37 weeks), n (%) | 6 (11) | 6 (13) | 4 (6) |
| Birthweight in grams, mean (σ) | 3340 (563)* | 3382 (604) | 3594 (517)* |
| Low birthweight, n (%) | 3 (5) | 4 (9) | 2 (3) |
| Small-for-gestational age, n (%) | 0 (0) | 3 (7) | 1 (2) |
| Caesarean section, n (%) | 15 (26) | 8 (17) | 19 (29) |
| Neonatal characteristics | |||
| NICU admission, n (%) | 1 (2) | 2 (4) | 4 (6) |
| Apgar score at 5 min <7b, n (%) | 0 (0) | 0 (0) | 0 (0) |
| Breastfed for >6 weeksb, n (%) | 29 (52) | 21 (46) | 33 (51) |
| Signs of foetal distressd, n (%) | 19 (33) | 12 (26) | 27 (41) |
| Parental characteristics | |||
| Maternal age at conception, median (range) | 33.2 (27.0–40.9) | 32.8 (26.2–37.5) | 33.7 (23.1–40.3) |
| Paternal age at conceptionb, median (range) | 36.4 (27.5–56.1)* | 33.7 (28.3–47.8)* | 35.4 (25.5–48.7) |
| Educational level mother highe, n (%) | 20 (35) | 20 (43) | 31 (47) |
| Educational level father highb,e, n (%) | 26 (48) | 15 (33) | 25 (38) |
| Cause of subfertilityf | |||
| Primary subfertility, n (%) | 31 (54) | 29 (63) | 32 (49) |
| Tubal pathology, n (%) | 11 (19) | 9 (20) | 5 (8) |
| Male factor, n (%) | 32 (56)** | 25 (54)* | 19 (29)**/* |
| Other causes, n (%) | 18 (32)* | 6 (13)* | 12 (18) |
| Unknown cause, n (%) | 7 (12)*** | 8 (17)*** | 35 (53)***/*** |
OS-IVF/ICSI: children born following ovarian stimulation IVF or ICSI, MNC-IVF/ICSI: children born following modified natural cycle IVF or ICSI, Sub-NC: naturally conceived children born to subfertile parents, NICU: neonatal intensive care unit.
* P < 0.05;**P < 0.01; ***P < 0.001 Student’s t-tests, Fisher’s exact tests and Mann–Whitney U-tests were performed to investigate differences between the groups.
Time to pregnancy (TTP) of the three ART groups was recorded in years and months and finally converted into decimal years. In case of a miscarriage, the onset of TTP was reset; therefore, TTP may be shorter than 1 year.
Missing data in three groups: Use of folic acid—OS-IVF: n = 3; Apgar score at 5 min <7—MNC-IVF: n = 1, OS-IVF: n = 1; breastfed >6 weeks—OS-IVF: n = 1, Sub-NC: n = 1; paternal age at conception—OS-IVF: n = 2, MNC-IVF: n = 1; educational level father—OS-IVF: n = 3, MNC-IVF: n = 1.
Birthweight for gestational age is below 2 SDs compared to a Dutch reference population.
Signs of foetal distress defined by meconium stained amniotic fluid and/or cardiotocographic signs and/or acidosis.
University education or vocational colleges.
Couples may have more than one cause of subfertility; therefore, totals may exceed 100%.