Table 1.

Papers included in meta-analysis of association between maternal use of analgesia during pregnancy and cryptorchidism, with study meta-data.

Author	Year of publication	Study design	Study period	Location of study	Sample size	Source of case / outcome data	Source of control / total cohort	Exclusion criteria	Method of outcome measurement	Timing of outcome measurement	Method of exposure measurement	Timing of exposure measurement
Banhidy et al.1	2007	CCS	1980 – 1996	Hungary	23,721 cases with congenital abnormalities (2,051 with crypt) 45,946 controls (38,151 matched healthy and 834 with Downs Syndrome)	Hungarian Congenital Abnormality Registry	Hungarian Birth Registry	Mild congenital abnormalities not included	Clinical diagnosis (reported to the Registry by obstetrician/paediatrician)	Reported during the first three months since birth	Maternal self-report (questionnaire), medical note review/antenatal logbook Face to face interview for non-respondents	Retrospective questionnaire 2nd and 3rd gestational months
Berkowitz et al.2	1996	Nested CCS	1987 –1990	New York City hospital	140 ‘late descenders’; 63 cases with crypt at one-year 203 controls	Hospital obstetrics service – all boys born during study period	Hospital obstetrics service – the next male infant born after case during study period	All multiple births	Clinical diagnosis	F/U clinical exam at 3 months and 1 year from expected delivery date	Parental questionnaire	Retrospective questionnaire administered during post-partum stay Medications during the index pregnancy
Davies et al.3	1986	CCS	1978 - 1986	UK	83 cases 129 controls	Hospital notes -crypt boys born in a single hospital and confirmed in Urological clinic	Two boys born just after each case – on the same day	All multiple births	Clinical diagnosis	Unspecified	Maternal face to face or phone Interview – GP confirmation of medical/pregnancy history	Retrospective
Mori et al.4	1992	CCS	1978 - 1986	Japan	104 crypt 104 matched controls	Discharge records or medical notes of two hospitals	Outpatients records at same two hospitals	Any multiple birth	Orchidopexy	Throughout childhood	Self-report questionnaire or face to face interview	Retrospective, throughout childhood (average child age 6.2 years)
Wagner-Mahler et al.5	2011	Nested CCS	2002 – 2005	France	95 cases 188 controls	Hospital records	Hospital records	Born before 34 weeks of amenorrhoea, stillbirth	Clinical diagnosis	Birth	Self-report questionnaire	Retrospective, during hospital stay after birth
Jensen et al.6	2010	Cohort	1996 - 2002	Denmark	47,400 women 980 crypt (565 with orchidopexy)	Danish National Patient Registry	Danish National Birth Cohort	Mother not intending to carry to term, not live birth, all multiple births, boys or mothers not uniquely identifiable	Clinical diagnosis Orchidopexy	Throughout childhood	Self-report questionnaire, then phone interview post-birth	Prospective, interviews at 17 and 32 gestational weeks; retrospective interviews 6 and 18 months after birth
Kristensen et al.7	2011	Cohort	1997-2001	Denmark and Finland	Denmark: 491 mothers Finland: 1,463 mothers	Hospital records	Hospital records	Non-usual residence in Denmark or Finland among parents and grandparents of the son	Clinical diagnosis	Denmark: Birth Finland: 18 months	Denmark: phone interview Finland: self-administered questionnaire	Prospective, third trimester
Philippat et al.8	2011	Cohort	2003 -2006	France	1st and 2nd trimester: 895 Whole pregnancy: 903 38 crypt cases	Hospital records from two hospital maternity units (Eden mother-child cohort)	Hospital records from two hospital maternity units (Eden mother-child cohort)	Any multiple birth	Clinical diagnosis	Within 3 days of birth	Questionnaire by midwives	Prospective, first and second trimesters
Rebordosa et al.9	2008	Cohort	1996 – 2003	Denmark	88,142 women	Danish National Patient Registry	Danish National Birth Cohort	Not intended to carry to term, non-Danish speaking, stillbirths, abortions (spontaneous and induced), ectopic pregnancies, hydatiform mole, twins, and triplets	Clinical diagnosis	Throughout childhood	Self-report questionnaire, and phone interviews	Prospective, only first trimester results presented for cryptorchidism
Snijder et al.10	2012	Cohort	2002 - 2006	Netherlands	3,184 women 68 crypt cases 3,094 normal boys	Determined during one of 10 visits to child health centres between 0-48 months	‘Generation R’ birth cohort	Lived outside of study area, had incomplete analgesic information	Clinical diagnosis	Between birth and 2 years of age	Self-report questionnaire	Prospective, three times during pregnancy (12, 20 and 30 gestational weeks)

CCS = case-control study.