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Table 1 Characteristics of the included studiesa

From: The association of prenatal and postnatal macrolide exposure with subsequent development of infantile hypertrophic pyloric stenosis: a systematic review and meta-analysis

Author, year Study design Country Study Interval Cases/subjects Exposure Adjusted risk estimate (95% CI) Quality Adjustment variables
Infant exposure
 Eberly,2015 [21] R-COH USA 2001–2012 2466/1074236 Erythromycin:
0–14 days
15–42 days
43–90 days
0–90 days
Azithromycin:
0–14 days
15–42 days
0–90 days
13.3 (6.8–25.9)
4.1 (1.69–9.91)
1.19 (0.38–3.71)
3.94 (2.44–6.36)
8.26 (2.62–26)
2.98 (1.24–7.2)
0.71 (0.36–1.43)
9 firstborn status, gender, and the year of the birth
 Ericson,2015 [22] R-COH USA 1997–2012 86/20196 Metoclopramide vs Erythromycin
(0–120 days)
0.52 (0.26–1.02) 9 Gestational age at birth, small-for-gestational-age status, severity of illness, and age at first medication exposure
 Lund,2014 [26] R-COH Denmark 1996–2011 849/998529 Erythromycin:
0–13 days
14–120 days
Rate Ratio:
29.8 (16.4–54.1)
3.24 (1.2–8.74)
9 birth order, gender, calendar period, current age of the infant, gestational age at birth, small for gestational age status, caesarean section, major congenital malformations, and maternal smoking during pregnancy
 Cooper, 2002 [19] R-COH USA 1985–1997 804/314029 Erythromycin:
3–13 days
14–27 days
28–90 days
Any use
incidence rate ratio:
7.88 (1.97–31.57)
0.92 (0.13–6.57)
1.95 (0.87–4.38)
2.05 (1.06–3.97)
9 Child’s age, sex, and race
 Mahon, 2001 [27] R-COH USA 1993–1999 43/14876 Erythromycin:
≤1 week
≤2 week
≤3 months
10.62 (4.2–26.7)
10.51 (4.5–24.7)
4.98 (2.1–11.7)
7 NR
 Honein,1999 [23] R-COH USA Jan - Feb, 1999 7/282 Erythromycin ∞ (1·7–∞) 6 Not adjusted
 Ludvigsson, 2016 [4] R-COH Sweden 2005–2010 450/582494 Macrolides
(0–120 days)
NR 6 NR
Maternal use during pregnancy
 Mahon, 2001 [27] R-COH USA 1993–1999 43/14876 Erythromycin:
Any time during pregnancy
1.19 (0.6–2.3) 7 NR
 Cooper, 2002 [20] R-COH USA 1985–1997 679/260799 Erythromycin:
Any time during pregnancy
≥ 32 weeks
Other macrolides:
Any time during pregnancy
≥ 32 weeks
1.15 (0.84–1.56)
1.17 (0.84–1.64)
2.77 (1.22–6.30)
2.45 (0.78–7.68)
9 sex, race, first-born status, year of birth, and infant’s postnatal prescriptions for erythromycin
 Källén, 2005 [24] R-COH Sweden 1995–2002 464/677028 Erythromycin:
Any time during pregnancy
1st trimester
2.51 (0.92–5.46)
3.03 (1.08–8.50)
7 NR
 Rookkapan, 2008 [25] R-COH Denmark 1991–2005 NR/176905 Erythromycin:
Any time during pregnancy
1.05 (0.43–2.55) 7 NR
 Dinur, 2013 [18] R-COH Israel 1999–2009 50/102831 Macrolides:
3rd trimester
NR 7 Not adjusted
 Lund,2014 [26] R-COH Denmark 1996–2011 877/999378 Macrolides:
0–27 weeks
≥28 weeks
1.02 (0.65–1.59)
1.77 (0.95–3.31)
9 birth order, sex, calendar period, and current age of the infant
 Louik, 2002 [29] C-C USA 1976–1998 1044/1704 Erythromycin:
1–24 weeks
25–40 weeks
33–40 weeks
1.0 (0.6–1.6)
0.6 (0.3–1.1)
0.7 (0.3–1.8)
8 maternal age, geographical region, study period, parity, sex of infants, gestational age
 Lin,2013 [28] C-C USA/Canada 1994 to 2008 735/6952 Erythromycin:
1st trimester
2nd trimester
3rd trimester
Macrolides:
1st trimester
2nd trimester
3rd trimester
0.9 (0.3–3.0)
1.5 (0.4–4.8)
1.5 (0.5–5.1)
1.3 (0.6–2.8)
1.3 (0.5–3.0)
1.3 (0.6–2.9)
8 residence and year, maternal age, race, education, pre-pregnancy BMI, family history of congenital malformations, diabetes mellitus, first trimester cigarette smoking, peri-conceptional folic acid supplement, multiple pregnancy, infections, sexually transmitted disease, febrile events
Maternal use after birth
 Lund,2014 [26] R-COH Denmark 1996–2011 849/999378 Macrolides:
0–13 days
14–120 days
Rate Ratio:
3.49 (1.92–6.34)
0.7 (0.26–1.9)
9 birth order, sex, calendar period, and current age of the infant, age at birth, small for gestational age, caesarean section, major congenital malformations, and maternal smoking during pregnancy
 SØRENSEN, 2003 [2] R-COH Denmark 1991–2000 78/35856 Macrolides:
(0–42 days)
2.8 (0.7–11.5) 9 maternal age, birth order and smoking status
  1. a Abbreviations: R-COH: Retrospective cohort studies; C-C: case-control studies; CI: Confidence Interval; NR: Not Reported