Table 1.

Characteristics of Included Studies

Study	Year	Country	Study Design	Inclusion Criteria	Exclusion Criteria	LEEP (n)	Unexposed
Haffenden	1993	UK	Retrospective cohort	Pregnancy post- LEEP	Birth < 24 weeks	152	Unknown dysplasia hx, no prior tx N= 152
Blomfield	1993	UK	Retrospective cohort	Pregnancy post- LEEP	Birth < 20 weeks	40	Unknown dysplasia hx, no prior tx N= 80
Braet	1994	UK	Retrospective cohort	1st pregnancy post-LEEP	Multiple gestation	78	Unknown dysplasia hx, no prior tx N= 78
Cruickshank	1995	UK	Retrospective cohort	1st pregnancy post-LEEP	Birth < 20 weeks, multiple gestation	149	Unknown dysplasia hx, no prior tx N= 298
Sadler	2004	New Zealand	Retrospective cohort	1st pregnancy post-LEEP	Birth < 20 weeks, multiple gestation, LEEP during pregnancy	278	Prior dysplasia, no prior tx N=426
Tan	2004	UK	Retrospective cohort	1st pregnancy post-LEEP	Age > 35 years	119	Unknown dysplasia hx, no prior tx N= 119
Acharya	2005	Norway	Retrospective cohort	1st pregnancy post-LEEP	Age >45 years, birth <20 weeks	79	Unknown dysplasia hx, no prior tx N= 158
Samson	2005	Canada	Retrospective cohort	1st pregnancy post-LEEP	Birth < 20 weeks, multiple gestation, prior PTB, indicated deliveries	571	Unknown dysplasia hx, no prior tx N=571
Crane	2006	Canada	Prospective cohort	Pregnancy post- LEEP	Multiple gestation	75	Unknown dysplasia hx, no prior tx N= 144
Nohr	2007	Denmark	Retrospective cohort	Pregnancy post- LEEP	Multiple gestation, indicated deliveries, stillbirth	349	Unknown dysplasia hx, no prior tx N= 14,567
Himes	2007	USA	Retrospective cohort	1st pregnancy post-LEEP	Birth < 20 weeks, multiple gestation, anomalies, LEEP during pregnancy	114	Prior dysplasia, no prior tx N= 962
Jakobsson	2007	Finland	Retrospective cohort	Pregnancy post- LEEP	Age > 49 years, age < 15 years, multiple gestation	2690	Unknown dysplasia hx, no prior tx N= 1,056,855
Ortoft	2010	Denmark	Retrospective cohort	Pregnancy post- LEEP	Multiple gestation, indicated deliveries	572	No hx of dysplasia or prior tx N=72,899
Werner	2010	USA	Retrospective cohort	1st pregnancy post-LEEP	Multiple gestation, LEEP during pregnancy	511	Unknown dysplasia hx, no prior tx N= 240,348 Prior dysplasia, no prior tx N= 842
Andia	2011	Spain	Retrospective cohort	Pregnancy post- LEEP	Multiple gestation	189	Unknown dysplasia hx, no prior tx N= 189 Prior dysplasia, no prior tx N= 189
Lima	2011	Portugal	Retrospective cohort	Pregnancy post- LEEP	None	18	Unknown dysplasia hx, no prior tx N= 58
Poon	2012	UK	Case control	Pregnancy post- LEEP	Multiple gestation, cerclage, anomalies, preterm PROM, contractions, progesterone, indicated deliveries	473	Unknown dysplasia hx, no prior tx N= 25,772
Van Hentenryck	2012	Belgium	Retrospective cohort	Pregnancy post- LEEP	None	40	Unk dysplasia hx, no prior tx N= 212
Simoens	2012	Belgium	Prospective cohort	Pregnancy post – EEP	Birth < 20 weeks, multiple gestation	52	No hx of dysplasia or prior tx N= 104

LEEP, loop electrosurgical excision procedure; hx, history; tx, treatment; PROM, premature rupture of membranes.