Table III.
The risk of preterm birth and SGA among ART singleton offspring with and without VTS, for all ART singletons born in Norway between July 1984 and December 2013.
| Outcome | VTS | Overall analysesa | Sibship analysesb | ||||
|---|---|---|---|---|---|---|---|
| N (% cases) | Unadjusted OR (95% CI) | Adjustedc OR (95% CI) | N (% cases) | Unadjusted OR (95% CI) | Adjustedc OR (95% CI) | ||
| Preterm birth (<37 weeks) | No | 16 038 (9) | Ref | Ref | 521 (50) | Ref | Ref |
| Yes | 583 (11) | 1.29 (0.92, 1.80) | 1.21 (0.87, 1.70) | 20 (55) | 1.21 (0.50, 2.92) | 1.21 (0.49, 3.00) | |
| Uncertaind | 2305 (9) | 0.97 (0.80, 1.17) | 0.91 (0.75, 1.10) | 46 (46) | 0.79 (0.37, 1.68) | 0.83 (0.38, 1.79) | |
| SGA (<10%) | No | 16 006 (9) | Ref | Ref | 584 (47) | Ref | Ref |
| Yes | 583 (12) | 1.52 (1.10, 2.09) | 1.48 (1.07, 2.03) | 26 (69) | 2.57 (1.06, 6.23) | 2.79 (1.12, 6.91) | |
| Uncertaind | 2299 (10) | 1.18 (0.99, 1.42) | 1.15 (0.96, 1.38) | 64 (58) | 1.76 (0.91, 3.41) | 1.97 (0.99, 3.93) | |
OR, odds ratio; SGA, small for gestational age.
aThe overall analyses was conducted using random-effects logistic regression, which compares the risk of the outcomes among all ART singletons with VTS to all ART singletons without VTS.
bThe sibship analyses was conducted using fixed-effects logistic regression, which compares the proportion with VTS between ART singletons discordant for the outcome of interest.
cAdjusted for maternal age, marital status, parity, year of birth and chronic diseases before pregnancy (asthma, hypertension, heart disease, kidney disease, rheumatoid arthritis, epilepsy, thyroid disease and diabetes).
dWhen information from the early ultrasound was missing, the status of VTS was defined as ‘uncertain’.