Unadjusted means and SDs of birth size, placental weight, and gestational age, according to mode of conception for liveborn singletons in Norway, 1988–2015.
| . | Population level, mean (SD) . | Within sibships1, mean (SD) . | ||||
|---|---|---|---|---|---|---|
| . | Natural conception n = 1 106 763 . | ART with fresh-ET n = 15 510 . | ART with frozen-ET n = 3093 . | Natural conception n = 6657 . | ART with fresh-ET n = 5871 . | ART with frozen-ET n = 1695 . |
| Birth length, cm | 50.3 (2.4) | 49.8 (2.8) | 50.5 (2.7) | 50.3 (2.5) | 49.9 (2.7) | 50.7 (2.6) |
| Birthweight, g | 3571 (544) | 3434 (594) | 3611 (609) | 3575 (566) | 3468 (582) | 3658 (578) |
| Head circumference, cm | 35.2 (1.6) | 34.9 (1.9) | 35.4 (1.9) | 35.2 (1.7) | 35.0 (1.8) | 35.5 (1.8) |
| Ponderal index, kg/m3 | 28.0 (2.6) | 27.5 (2.7) | 27.8 (2.7) | 28.0 (2.7) | 27.6 (2.6) | 27.9 (2.6) |
| Placental weight2, g | 675 (147) | 675 (154) | 702 (167) | 680 (152) | 680 (155) | 711 (168) |
| Birthweight:placental weight ratio1 | 5.43 (0.94) | 5.22 (0.95) | 5.29 (0.97) | 5.41 (0.96) | 5.25 (0.95) | 5.30 (0.97) |
| Gestational age, days | 280.2 (12.2) | 277.4 (14.5) | 278.7 (14.7) | 279.3 (12.8) | 277.5 (13.7) | 279.0 (13.6) |
| Birthweight z-score3 | 0.00 (1.17) | −0.18 (1.17) | 0.20 (1.20) | 0.06 (1.17) | −0.10 (1.16) | 0.29 (1.16) |
| . | Population level, mean (SD) . | Within sibships1, mean (SD) . | ||||
|---|---|---|---|---|---|---|
| . | Natural conception n = 1 106 763 . | ART with fresh-ET n = 15 510 . | ART with frozen-ET n = 3093 . | Natural conception n = 6657 . | ART with fresh-ET n = 5871 . | ART with frozen-ET n = 1695 . |
| Birth length, cm | 50.3 (2.4) | 49.8 (2.8) | 50.5 (2.7) | 50.3 (2.5) | 49.9 (2.7) | 50.7 (2.6) |
| Birthweight, g | 3571 (544) | 3434 (594) | 3611 (609) | 3575 (566) | 3468 (582) | 3658 (578) |
| Head circumference, cm | 35.2 (1.6) | 34.9 (1.9) | 35.4 (1.9) | 35.2 (1.7) | 35.0 (1.8) | 35.5 (1.8) |
| Ponderal index, kg/m3 | 28.0 (2.6) | 27.5 (2.7) | 27.8 (2.7) | 28.0 (2.7) | 27.6 (2.6) | 27.9 (2.6) |
| Placental weight2, g | 675 (147) | 675 (154) | 702 (167) | 680 (152) | 680 (155) | 711 (168) |
| Birthweight:placental weight ratio1 | 5.43 (0.94) | 5.22 (0.95) | 5.29 (0.97) | 5.41 (0.96) | 5.25 (0.95) | 5.30 (0.97) |
| Gestational age, days | 280.2 (12.2) | 277.4 (14.5) | 278.7 (14.7) | 279.3 (12.8) | 277.5 (13.7) | 279.0 (13.6) |
| Birthweight z-score3 | 0.00 (1.17) | −0.18 (1.17) | 0.20 (1.20) | 0.06 (1.17) | −0.10 (1.16) | 0.29 (1.16) |
Fresh-ET, fresh embryo transfer; frozen-ET, frozen embryo transfer.
Sibships with at least two of the three different conception methods.
Number of observations in analyses of placental weight at the population level: NC n = 729 308, fresh-ET n = 13 317, frozen-ET n = 2926; within sibships: NC n = 5013, fresh-ET n = 4641, frozen-ET n = 1512.
Birthweight z scores are defined as standard deviations according to gestational age in days and sex using Marsal’s formulas.
Unadjusted means and SDs of birth size, placental weight, and gestational age, according to mode of conception for liveborn singletons in Norway, 1988–2015.
| . | Population level, mean (SD) . | Within sibships1, mean (SD) . | ||||
|---|---|---|---|---|---|---|
| . | Natural conception n = 1 106 763 . | ART with fresh-ET n = 15 510 . | ART with frozen-ET n = 3093 . | Natural conception n = 6657 . | ART with fresh-ET n = 5871 . | ART with frozen-ET n = 1695 . |
| Birth length, cm | 50.3 (2.4) | 49.8 (2.8) | 50.5 (2.7) | 50.3 (2.5) | 49.9 (2.7) | 50.7 (2.6) |
| Birthweight, g | 3571 (544) | 3434 (594) | 3611 (609) | 3575 (566) | 3468 (582) | 3658 (578) |
| Head circumference, cm | 35.2 (1.6) | 34.9 (1.9) | 35.4 (1.9) | 35.2 (1.7) | 35.0 (1.8) | 35.5 (1.8) |
| Ponderal index, kg/m3 | 28.0 (2.6) | 27.5 (2.7) | 27.8 (2.7) | 28.0 (2.7) | 27.6 (2.6) | 27.9 (2.6) |
| Placental weight2, g | 675 (147) | 675 (154) | 702 (167) | 680 (152) | 680 (155) | 711 (168) |
| Birthweight:placental weight ratio1 | 5.43 (0.94) | 5.22 (0.95) | 5.29 (0.97) | 5.41 (0.96) | 5.25 (0.95) | 5.30 (0.97) |
| Gestational age, days | 280.2 (12.2) | 277.4 (14.5) | 278.7 (14.7) | 279.3 (12.8) | 277.5 (13.7) | 279.0 (13.6) |
| Birthweight z-score3 | 0.00 (1.17) | −0.18 (1.17) | 0.20 (1.20) | 0.06 (1.17) | −0.10 (1.16) | 0.29 (1.16) |
| . | Population level, mean (SD) . | Within sibships1, mean (SD) . | ||||
|---|---|---|---|---|---|---|
| . | Natural conception n = 1 106 763 . | ART with fresh-ET n = 15 510 . | ART with frozen-ET n = 3093 . | Natural conception n = 6657 . | ART with fresh-ET n = 5871 . | ART with frozen-ET n = 1695 . |
| Birth length, cm | 50.3 (2.4) | 49.8 (2.8) | 50.5 (2.7) | 50.3 (2.5) | 49.9 (2.7) | 50.7 (2.6) |
| Birthweight, g | 3571 (544) | 3434 (594) | 3611 (609) | 3575 (566) | 3468 (582) | 3658 (578) |
| Head circumference, cm | 35.2 (1.6) | 34.9 (1.9) | 35.4 (1.9) | 35.2 (1.7) | 35.0 (1.8) | 35.5 (1.8) |
| Ponderal index, kg/m3 | 28.0 (2.6) | 27.5 (2.7) | 27.8 (2.7) | 28.0 (2.7) | 27.6 (2.6) | 27.9 (2.6) |
| Placental weight2, g | 675 (147) | 675 (154) | 702 (167) | 680 (152) | 680 (155) | 711 (168) |
| Birthweight:placental weight ratio1 | 5.43 (0.94) | 5.22 (0.95) | 5.29 (0.97) | 5.41 (0.96) | 5.25 (0.95) | 5.30 (0.97) |
| Gestational age, days | 280.2 (12.2) | 277.4 (14.5) | 278.7 (14.7) | 279.3 (12.8) | 277.5 (13.7) | 279.0 (13.6) |
| Birthweight z-score3 | 0.00 (1.17) | −0.18 (1.17) | 0.20 (1.20) | 0.06 (1.17) | −0.10 (1.16) | 0.29 (1.16) |
Fresh-ET, fresh embryo transfer; frozen-ET, frozen embryo transfer.
Sibships with at least two of the three different conception methods.
Number of observations in analyses of placental weight at the population level: NC n = 729 308, fresh-ET n = 13 317, frozen-ET n = 2926; within sibships: NC n = 5013, fresh-ET n = 4641, frozen-ET n = 1512.
Birthweight z scores are defined as standard deviations according to gestational age in days and sex using Marsal’s formulas.
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