A firstborn boy is suggestive of a strong prognostic factor in secondary recurrent miscarriage: a confirmatory study.
OBJECTIVE
To test our previously generated hypothesis that women with secondary recurrent miscarriages with a firstborn boy have a poorer pregnancy prognosis than those with a firstborn girl.


METHODS
A study of a retrospective and a prospective cohort.


METHODS
The Danish recurrent miscarriage clinic.


METHODS
Two cohorts of 175 and 130 consecutive patients with unexplained secondary recurrent miscarriage referred from 1986 to 1999 (cohort 1) and 2000 to 2005 (cohort 2), respectively.


METHODS
The odds ratio (OR) for a live birth in the first pregnancy after referral in those with a firstborn boy compared with a firstborn girl in each of the two cohorts. The corresponding OR for a live birth adjusted for relevant prognostic variables in the combined group of patients.


RESULTS
The crude ORs for a live birth in those with a firstborn boy compared with a firstborn girl were very similar in cohorts 1 and 2 (OR = 0.35, 0.33). In the adjusted analysis only two of five included variables significantly predicted live birth: a firstborn boy and the number of previous miscarriages.


CONCLUSIONS
Male sex of the firstborn child is a strong negative prognostic factor in women with secondary recurrent miscarriage. A possible explanation is an abnormal maternal immune response against male-specific minor histocompatibility (HY) antigens.
Nielsen
Henriette Svarre
HS
The Fertility Clinic, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. henriettesvarrenielsen@hotmail.com
Andersen
Anne-Marie Nybo
AM
Kolte
Astrid Marie
AM
Christiansen
Ole Bjarne
OB
D000026:Abortion, Habitual / Q000209:etiology* / Q000276:immunology; D000328:Adult; D005260:Female; D006182:H-Y Antigen / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D050498:Live Birth; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D011247:Pregnancy; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012744:Sex Ratio
D006182:H-Y Antigen