Table 1

Main meta-analyses

Outcome	Exposure/insult		K	OR	95% CI		P value	Heterogeneity
Outcome	Exposure/insult		K	OR	Lower limit	Upper limit	P value	I² (%)	P value
All BPD (BPD28)	Hypertensive disorders of pregnancy (HDP)	Any HDP	13	0.927	0.636	1.352	0.695	62.8	0.001
		Pre-eclampsia	14	1.058	0.756	1.482	0.742	59.4	0.002
		Pre-eclampsia/HELLP	6	0.771	0.465	1.279	0.314	64.7	0.015
		HDP overall	33	0.949	0.757	1.188	0.645	61.9	<0.001
	SGA/IUGR	BW <P10	27	0.823	0.618	1.096	0.182	64.7	<0.001
		BW <P3 or −2SD	4	1.234	0.599	2.541	0.569	82.9	0.001
		IUGR	2	1.267	0.532	3.018	0.535	0.0	0.546
		IUGR/SGA overall	33	0.898	0.696	1.158	0.408	66.2	<0.001
Moderate/severe BPD (BPD36)	HDP	Any HDP	27	1.066	0.914	1.243	0.810	68.9	<0.001
		Pre-eclampsia	31	1.093	0.869	1.375	0.448	83.8	<0.001
		Pre-eclampsia/HELLP	3	1.022	0.762	1.372	0.882	75.8	0.017
		HDP overall	61	1.066	0.948	1.198	0.288	79.8	<0.001
	SGA/IUGR	BW <P10	57	1.550	1.308	1.837	<0.001	85.7	<0.001
		BW <P5	2	1.651	0.659	4.138	0.284	0.0	0.674
		BW <P3 or −2SD	23	1.460	1.130	1.884	0.004	87.8	<0.001
		IUGR	9	2.251	1.537	3.297	<0.001	80.0	<0.001
		SGA/IUGR overall	91	1.564	1.369	1.785	<0.001	85.5	<0.001
Severe BPD	HDP	HDP overall*	8	0.940	0.582	1.517	0.799	41.8	0.100
	SGA/IUGR	BW <P10	11	1.491	1.001	2.220	0.049	34.5	0.123
		BW <P3	4	2.277	1.296	4.031	0.005	0.0	0.788
		IUGR	2	2.285	1.220	4.290	0.010	71.6	0.061
		SGA/IUGR overall	17	1.821	1.363	2.288	<0.001	24.5	0.171
BPD or death	HDP	HDP overall*	8	0.771	0.635	0.937	0.009	38.9	0.120
	SGA/IUGR	BW <P10	12	1.792	1.387	2.315	<0.001	90.5	<0.001
		BW <P5	1	2.970	0.899	9.814	0.074	0.0	1.000
		BW <P3 or −2SD	2	2.538	1.323	4.869	0.005	54.1	0.140
		IUGR	3	1.934	1.126	3.323	0.017	87.7	<0.001
		SGA/IUGR overall	18	1.914	1.545	2.373	<0.001	88.7	<0.001
BPD-associated pulmonary hypertension	HDP	Any HDP	11	1.408	1.034	1.917	0.030	38.3	0.094
		Pre-eclampsia	9	1.418	0.944	2.128	0.092	0.0	0.554
		HDP overall	20	1.412	1.104	1.805	0.006	18.3	0.227
	SGA/IUGR	BW <P10	17	2.275	1.771	2.922	<0.001	40.8	0.041
		BW <P3 or −2SD	3	4.418	1.689	11.556	0.002	0.0	0.390
		SGA/IUGR overall	20	2.373	1.862	3.023	<0.001	38.7	0.040

Mixed effects analysis. A random effects model is used to combine studies within each subgroup. A fixed effect model is used to combine subgroups and yield the overall effect.
*Studies were not divided into subgroups because K<10 . OR >1 indicates association with increased risk of the outcome and OR <1 indicates association with decreased risk of the outcome.
BPD28, BPD defined as oxygen requirement on postnatal day 28; BPD36, BPD defined as oxygen requirement at the postmenstrual age of 36 weeks; BPD, bronchopulmonary dysplasia; BW, birth weight; IUGR, intrauterine growth restriction (defined on the basis of fetal growth assessment); K, number of studies; P3, third percentile; P5, 5th percentile; P10, 10th percentile; SGA, small for gestational age.