Risk factors for parvovirus B19 infection in pregnancy.
BACKGROUND
Parvovirus B19 infection during pregnancy has been associated with fetal death. However, the incidence of and risk factors for infection in pregnant women have not been well studied.


OBJECTIVE
To estimate a pregnant woman's risk of infection with parvovirus B19 in epidemic and endemic situations and to study risk factors for infection.


METHODS
Population-based cohort study conducted between November 1992 and June 1994.


METHODS
Three regions in Denmark.


METHODS
A total of 30946 pregnant women from a consecutive and population-based screening.


METHODS
Specific IgG antibodies in serum samples obtained in the first trimester of pregnancy and from the newborn infant to assess past infection and seroconversion. Information on family structure, educational background, socioeconomic status, and pregnancy outcome was obtained from national registers.


RESULTS
Based on 30 946 serum samples, 65.0% of pregnant women had evidence of past infection. Annual seroconversion rates among susceptible women during endemic and epidemic periods were 1.5% (95% confidence interval [CI], 0.2%-1.9%) and 13.0% (95% CI, 8.7%-23.1 %), respectively. Baseline seropositivity was significantly correlated with increasing number of siblings, having a sibling of the same age, number of own children, and occupational exposure to children. Risk of acute infection increased with the number of children in the household as follows: 0 children odds ratio (OR), 1 (reference); 1 child OR, 3.17 (95% CI, 2.24-4.49); 2 children OR, 5.47 (95% CI, 3.55-8.45); 3 or more children OR, 7.54 (95% CI, 3.80-14.94). Having children aged 6 to 7 years resulted in the highest rate of seroconversion among mothers (6.8%; OR, 4.07; 95% CI, 1.89-8.73). Compared with other pregnant women, nursery school teachers had a 3-fold increased risk of acute infection (OR, 3.09; 95% CI, 1.62-5.89). Population-attributable risk of seroconversion was 55.4% for number of own children and 6.0% for occupational exposure.


CONCLUSIONS
The risk of infection is high for susceptible pregnant women during epidemics and associated with the level of contact with children. Nursery school teachers have the highest occupational risk, but most infections seem to be the result of exposure to the woman's own children.
Valeur-Jensen
A K
AK
Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut, Copenhagen.
Pedersen
C B
CB
Westergaard
T
T
Jensen
I P
IP
Lebech
M
M
Andersen
P K
PK
Aaby
P
P
Pedersen
B N
BN
Melbye
M
M
D000208:Acute Disease; D000328:Adult; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D016731:Erythema Infectiosum / Q000453:epidemiology* / Q000635:transmission; D005191:Family Characteristics; D005260:Female; D006801:Humans; D016273:Occupational Exposure; D016732:Parvovirus B19, Human; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D012042:Registries; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012959:Socioeconomic Factors