Obstetrical deliveries associated with maternal malignancy in California, 1992 through 1997

OBJECTIVE: This study aims to characterize the rate of occurrence and natur e of outcomes associated with obstetrical deliveries in women with malignan t neoplasms among 3,168,911 women who delivered in California in 1992 throu gh 1997. DESIGN: The study is a population-based retrospective review of infant birt h and death certificates and maternal and neonatal discharge records. Cases of malignant neoplasms associated with obstetrical delivery were attribute d to 1 of 3 categories, depending on the earliest documented hospital disch arge diagnosis. as follows: "prenatal" ii the diagnosis was first documente d by hospitalization within 9 months preceding delivery, "at delivery" ii t he diagnosis was established from the delivery hospitalization, or "postpar tum" if the diagnosis was first documented by hospitalization within 12 mon ths after delivery. METHODS: Computer-linked infant birth and death certificates and maternal a nd neonatal discharge records were used to identify cases and outcomes. Cas es of malignant neoplasms were identified by using International Classifica tion of Diseases, Ninth Revision codes (140-208). Noninvasive neoplasms and carcinoma in situ neoplasms were excluded. In analysis of outcomes, the Ma ntel-Haenszel estimate for adjusted odds ratios was used. RESULTS: Among 3,168,911 obstetrical deliveries over the 6-year span, a tot al of 2247 cases of primary malignancy were identified. The observed rate o f occurrence for primary malignant neoplasms was 0.71 per 1000 live singlet on births. Most cases (53.3%) were first documented in the postpartum perio d as follows: prenatal, 587 cases (0.18 per 1000); at delivery, 462 cases ( 0.15 per 1000); and postpartum, 1198 cases (0.38 per 1000). The most freque ntly documented primary malignant neoplasms associated with obstetrical del ivery were breast cancer (423 cases, 0.13 per 1000), thyroid cancer (389 ca ses, 0.12 per 1000), cervical cancer (266 cases, 0.08 per 1000), Hodgkin's disease (172 cases, 0.05 per 1000), and ovarian cancer (123 cases, 0.04 per 1000). Odds ratios for a variety of demographic factors identified materna l age as the most significant risk factor for development of malignant neop lasms (age greater than 40 vs 20-25, odds ratio 5.7, CI 4.6-6.9). Age-adjus ted odds ratios for maternal cancer of any type suggested significantly ele vated risks for cesarean delivery (odds ratio 1.4, CI 1.3-1.6), blood trans fusion (odds ratio 6.2, CI 4.5-8.5), hysterectomy (odds ratio 27.4, CI 20.8 -36.1), and maternal postpartum hospital stay greater than 5 days (odds rat io 30.6, Cl 27.9-33.6), but not for postpartum maternal death (odds ratio 0 .8, Cl 0.6-1.0). Odds ratios also suggested significantly elevated risks fo r premature newborn (odds ratio 2.0, Cl 1.8-2.2), very low birth weight (od ds ratio 2.9, Cl 2.2-3.8), and newborn hospital slay longer than 5 days (od ds ratio 2.6, Cl 2.4-3.0), but not for neonatal death (odds ratio 1.6, Cl 0 .8-3.1) or infant death (odds ratio 1.2, Cl 0.5-3.3). However, several type s of malignant neoplasms did confer significant elevations in risk for neon atal death. Hospital charges for both maternal and neonatal care were signi ficantly elevated in the maternal malignant neoplasm group. CONCLUSION: A lower than expected occurrence rate of obstetrical delivery a ssociated with maternal malignancy was seen when compared with previously p ublished hospital-based reports. Malignant neoplasms associated with obstet rical delivery were most frequently first documented in the postpartum peri od. Maternal and neonatal morbidity were significantly increased, yet the r isk of in-hospital maternal death was not significantly elevated. A signifi cant increase in risk oi neonatal death for infants of mothers with cervica l cancer was found.