Serial assessment of amniotic fluid index in uncomplicated term pregnancies: prognostic value of amniotic fluid reduction.

OBJECTIVE: Assessment of amniotic fluid volume in association with a non-stress test is a commonly used method to monitor fetal well-being in high-risk pregnancies. The aims of our study were to determine whether oligohydramnios and the trend in amniotic fluid volume have prognostic significance in low-risk pregnancies between 40.0 and 41.6 weeks' gestation. METHODS: Between January 1997 and December 2000, all uncomplicated gestations with a singleton non-anomalous fetus reaching 40.0 weeks' gestation underwent semi-weekly monitoring of amniotic fluid index (AFI) until delivery. Oligohydramnios was defined as an AFI of < or = 5 cm. Changes in AFI were expressed as centimeters per day, and were calculated as: [(last AFI before delivery minus first AFI at 40.0 weeks) / interval in days between the two scans]. Adverse outcome was considered the occurrence of 5-min Apgar score < 7; umbilical artery pH < 7.0; Cesarean section for fetal distress; or fetal death. Comparisons between the groups with favorable and adverse outcomes was performed with chi(2) or Fisher's exact test for categorical variables, and Student's t test for continuous variables. A two-tailed p value < 0.05 was considered significant. RESULTS: A total of 3050 women met the study criteria, and underwent a median number of two (range 1-7) sonographic assessments of AFI after 40.0 weeks, with oligohydramnios detected in 341 women. In 1466 women at least two serial AFI determinations were obtained, allowing computation of an AFI trend. Gestations resulting in adverse perinatal outcome (n = 167, 5.5%) had a significantly higher rate of oligohydramnios (33/167, 19.8% vs. 308/2883, 10.7%, p = 0.001), but a similar rate of reduction in AFI ( -0.65 +/- 0.64 vs. - 0.66 +/- 0.66 cm/day; p = 0.85) than those with favorable outcome. The difference in rate of reduction of AFI between the two groups was not significant, even in the subset of gestations that developed oligohydramnios ( -1.08 +/- 0.87 vs. -1.26 +/- 0.89 cm/day; p = 0.27). CONCLUSION: A sonographic diagnosis of oligohydramnios carries an increased risk of adverse perinatal outcome, even in low-risk pregnancies after 40 weeks. The trend in amniotic fluid volume reduction does not seem to have prognostic significance.

Pathology findings in preterm placentas of women with autoantibodies: a case-control study.

OBJECTIVE: To evaluate the placental histopathology findings in women with systemic lupus erythematosus or antiphospholipid syndrome delivered preterm. METHODS: We performed a case-control study comparing clinical outcomes and placental histopathology of 18 consecutive singleton pregnancies with systemic lupus erythematosus (n = 9) or antiphospholipid syndrome (n = 9) delivered between 24 and 37 weeks, and 54 controls matched for gestational age and type of preterm delivery (spontaneous or indicated). Placental examinations were performed by a single pathologist, and placental lesions were grouped into four categories: uteroplacental vascular pathology and related villous lesions; coagulation-related damage; chronic inflammation; and acute inflammatory lesions. Statistical analysis included the Mantel-Haenzsel or Fisher's exact test, and logistic regression, with a value of p < 0.05 or an odds ratio (OR) with 95% confidence intervals (Cl) not inclusive of unity considered significant. RESULTS: Lupus anticoagulant was positive in ten out of 18 cases and medium or high positive IgG anticardiolipin antibodies in seven out of 18. Antenatal treatment included corticosteroids (n = 9), low-dose aspirin (n = 15) and heparin (n = 8). Rates of necrotizing enterocolitis (33% vs. 0%, p < 0.001) and of perinatal mortality (33% vs. 9%, p = 0.02) were significantly different between cases and controls, and rates of birth weight < 10th centile approached statistical significance. Uteroplacental vascular lesions (OR 3.7, 95% CI 1.1, 11.7) and coagulation-related damage (OR 16.8, 95% CI 3.9, 72.6) were significantly more common among cases than controls, and rates of chronic inflammatory lesions approached significance. CONCLUSIONS: Cases of systemic lupus erythematosus and antiphospholipid syndrome delivered preterm are associated with a significant increase in placental vascular and coagulation-related lesions, which are reflected clinically by higher rates of perinatal mortality, necrotizing enterocolitis, and small-for-gestational age neonates.