Association between loop electrosurgical excision procedure and adverse pregnancy outcomes: a meta-analysis

Figures & data

Figure 1. Flow chart of the study selection process.

Table 1. Baseline characteristics of included studies.

Author	Year	Country	Study design	Definition of preterm birth	Definition of low birth weight	With LEEP		Without LEEP		Quality assessment	Outcomes
						n	Age	N	age
Blomfield	1993	UK	Retrospective cohort	<36 weeks		40	26(23–31) ^a	80	25(23–30) ^a	6	①
Haffenden	1993	UK	Retrospective cohort	<37 weeks		152		152		3	①
Braet	1994	UK	case-control	24–37 weeks	<2500 g	78	25.8 ± 3.9	78	25.7 ± 3.8	5	①③④
Cruickshank	1995	UK	Retrospective cohort	<37 weeks		149	27.7(19–44) ^a	298	27.6(18-43) ^a	4	①⑤
Paraskevaidis	2002	Greece	case-control	<37 weeks		28		28		6	①
Sadler	2004	New Zealand	Retrospective cohort	<37 weeks		278		426		6	①
Tan	2004	UK	Retrospective cohort	<37 weeks		119	27.5	119	27.7	5	①⑤
Acharya	2005	Norway	Prospective cohort	<37 weeks		79	27(19–36) ^a	158		7	①④
Samson	2005	Canada	Retrospective cohort	<37 weeks		571	28.99	571	28.99	8	①②④
Crane	2006	Canada	Prospective cohort	<37 weeks		75	29.4 ± 4.5	144		8	①④
Nøhr	2007	Denmark	prospective cohort	21–37 weeks		349	(20–29) ^a	14567	(20–29) ^a	5	①
Jakobsson	2007	Finland	retrospective cohort	<37 weeks		2690	(15–49) ^a	1056855	(15–49) ^a	6	①
Himes	2007	USA	Retrospective cohort	<37 weeks		114		962		7	①
Noehr	2009	Denmark	cohort study	21–36 weeks		8180	31.5 ± 3.8	544498	30.0 ± 4.8	5	①
Noehr(1)	2009	Denmark	cohort study	21–37 weeks		166	31.8 ± 3.8	9702	30.9 ± 4.4	7	①
Ortoft	2010	Denmark	Retrospective cohort	<37 weeks		572		72899		7	①
Lima	2011	Portugal	retrospective cohort	<37 weeks		18	28.3 ± 4.5	58	29 ± 5.7	5	①
Andia	2011	Spain	case-control	<37 weeks	<2500 g	189		378		6	①③
Simoens	2012	Belgium	Prospective cohort	<37 weeks		52		104		7	①
Poon	2012	UK	case-control	< 36 weeks		473		25772		5	①
Kitson	2013	UK	cohort study	<37 weeks		278	30(23–45) ^a	278	30(24–53) ^a	7	①
Heinonen	2013	Finland, Sweden	retrospective cohort	<37 weeks		7636	30.8 ± 4.8	658179	30.0 ± 5.5	5	①
Guo	2013	China	cohort study	<37 weeks		48	29.8 ± 5.1	68	31.0 ± 4.0	5	①②
Frega	2013	Italy	case-control	24–36 weeks		475	30.8 ± 3.9	441	31.9 ± 4.0	6	①⑤
Ciavattini	2015	Italy	retrospective cohort			640	35 ± 4.9	398	35 ± 5.3	6	⑤
Heinonen	2018	Finland	cohort study	<37 weeks		797	31.4	2220	30.1	5	①
Yu	2019	China	cohort study	<37 weeks		125	27.97 ± 3.47	500	28.02 ± 3.04	6	①
Veleva	2019	Bulgaria	cohort study	<37 weeks		62	31.5 ± 4.0	192	31.9 ± 4.3	4	①
Miyakoshi	2019	Japan	retrospective cohort	<37 weeks	<2500 g	1389	33.8	1389	33.8	5	①②③
Maina	2019	Italy	retrospective cohort	<37 weeks		148	35.00 ± 4.48	57937	33.78 ± 4.30	6	①

Notes: ^a Represents extreme value; LEEP: Loop Electrosurgical Excision Procedure; Outcomes: ① Preterm delivery; ② Premature rupture of membrane (PROM);③ Low birth weight; ④ Perinatal death; ⑤ Miscarriage.

Figure 2. The forest plot of risk of preterm delivery between LEEP group and control group; (a) overall analysis of preterm delivery; (b) subgroup analysis of preterm delivery.

Table 2 Overall and subgroup meta-analysis results.

Outcome and subgroup	OR (95%CI)	p	I^2
Premature birth
Design
Cohort	2.193(1.808–2.659)	<0.001	88.1
Case-Control	1.648(1.275–2.130)	<0.001	14.9
Overall	2.100(1.762–2.503)	<0.001	86.0
Sensitivity analysis	2.100(1.762–2.503)
Premature rupture of fetal membranes
Overall	1.989(1.630–2.428)	<0.001	40.4
Sensitivity analysis	1.989(1.630–2.428)
Low birth weight infant
Design
Cohort	1.949(1.607-–2.365)	<0.001	NA
Case-Control	1.856(1.093–3.150)	0.022	23.0
Overall	1.939(1.617–2.324)	<0.001	0.0
Sensitivity analysis	1.939(1.617–2.324)
Perinatal mortality
Design
Cohort	2.440(0.597–9.975)	0.214	0.0
Case-Control	3.039(0.122–75.746)	0.498	NA
Overall	2.538(0.700–9.202)	0.156	0.0
Sensitivity analysis	2.538(0.700–9.202)
Miscarriage
Design
Cohort	1.471(1.066–2.029)	0.019	0.0
Case-Control	1.039(0.717–1.505)	0.84	NA
Overall	1.270(0.997–1.617)	0.053	0.0
Sensitivity analysis	1.270(0.997–1.617)

Figure 3. The forest plot of risk of premature rupture of fetal membranes between LEEP group and control group.

Figure 4. The forest plot of low birth weight infants between LEEP group and control group.

Figure 5. The forest plot of perinatal mortality between LEEP group and control group.

Figure 6. The forest plot of miscarriage between LEEP group and control group.