Maternal, delivery, and perinatal characteristics associated with cryptorchidism: a population-based case-control study among births in Washington State.
BACKGROUND
The etiology of cryptorchidism is largely unknown. To identify maternal, perinatal, and delivery characteristics associated with cryptorchidism at birth, we conducted a population-based case-control study using Washington State birth certificates linked to birth hospitalization records.


METHODS
We identified 2,395 cases of cryptorchidism among male infants born in Washington State during 1986-1996, and, for comparison, we randomly selected four controls per case (N = 9,580), frequency-matched by year of birth.


RESULTS
Infant characteristics associated with cryptorchidism included low birth weight (OR = 1.5; 95% CI = 1.3-1.8), small size for gestational age (OR = 1.9; 95% CI = 1.6-2.2), and breech presentation (OR = 1.7; 95% CI = 1.4-2.1). In addition to cryptorchidism, cases were more likely to have another type of congenital malformation (OR = 3.7; 95% CI = 3.2-4.2), particularly digestive (OR = 6.8; 95% CI = 3.7-12.7) or genitourinary (OR = 4.1; 95% CI = 3.0-5.6). Maternal and pregnancy characteristics associated with cryptorchidism included nulliparity (OR = 1.2; 95% CI = 1.1-1.3), maternal smoking during pregnancy (OR = 1.2; 95% CI = 1.1-1.4), and the following pregnancy complications: oligohydramnios (OR = 1.8; 95% CI = 1.3-2.6), placental abnormality (OR = 1.3; 95% CI = 1.0-1.8), and pregnancy-induced hypertension (OR = 1.6; 95% CI = 1.4-1.9). Odds ratios were similar when the analysis was restricted to term infants.


CONCLUSIONS
These findings suggest that factors affecting fetal growth and development may increase the risk of cryptorchidism.
Biggs
Mary Lou
ML
Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle, WA 98195, USA. mlbiggs@u.washington.edu
Baer
Atar
A
Critchlow
Cathy W
CW
D000328:Adult; D001724:Birth Weight; D016022:Case-Control Studies; D003456:Cryptorchidism / Q000453:epidemiology*; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D007752:Obstetric Labor, Premature; D016104:Oligohydramnios / Q000453:epidemiology; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D012307:Risk Factors; D014861:Washington / Q000453:epidemiology