Gestational age and fetal growth in relation to maternal ovarian cancer risk in a Swedish cohort.
BACKGROUND
Pregnancy influences subsequent maternal ovarian cancer risk. To date, there is limited evidence whether two characteristics of pregnancy, gestational age and birth weight, could modify risk.


METHODS
We studied 1.1 million Swedish women who delivered singleton births between 1973 and 2001. Information on infant gestational age and birth weight was abstracted from the nationwide Swedish Birth Register. Women were followed prospectively through linkage with other population-based registers for occurrence of ovarian cancer, death, or emigration through 2001. Hazard ratios [relative risk (RR), 95% confidence interval (95% CI)] from Cox models were used to estimate associations between gestational age, birth weight, and epithelial ovarian cancer risk.


RESULTS
During 12.6 million person-years, 1,017 epithelial ovarian cancers occurred. Mean age at diagnosis was 43 years. Compared with women with term deliveries (>/=40 weeks), women with moderately (35-36 weeks) or very (<35 weeks) preterm deliveries had increased risks of epithelial ovarian cancer (RR 1.4, 95% CI 1.0-2.0 and RR 2.3, 95% CI 1.3-3.8, respectively). In contrast, women giving birth to small-for-gestational-age babies had a reduced risk (RR 0.7, 95% CI 0.4-1.0). Stratifying on birth weight and gestational age, there was a strong protective effect of low birth weight on maternal risk of epithelial ovarian cancer among term deliveries, whereas birth weight seemed to have little effect among preterm births (P(interaction) = 0.022).


CONCLUSIONS
Our results lend further support that the hormonal milieu of a pregnancy may modify long-term risk of developing ovarian cancer. 32).
Mucci
Lorelei A
LA
Channing Laboratory, Harvard Medical School/Brigham and Women's Hospital, 181 Longwood Avenue, 3rd Floor, Boston, MA 02115, USA. lmucci@hsph.harvard.edu
Dickman
Paul W
PW
Lambe
Mats
M
Adami
Hans-Olov
HO
Trichopoulos
Dimitrios
D
Riman
Tomas
T
Hsieh
Chung-Cheng
CC
Cnattingius
Sven
S
D000328:Adult; D005260:Female; D047109:Fetal Development; D005865:Gestational Age; D006801:Humans; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000209:etiology*; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic; D016016:Proportional Hazards Models; D012306:Risk; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors