Richard L. Fischer

Fetal growth and the etiology of preterm delivery

Objective To confirm that preterm delivery is associated with fetal growth restriction (FGR), and to determine if the various etiologies of preterm delivery are associated with the same degree and type of FGR. Methods Two hundred ninety young, primarily minority gravidas who had routine initial ultrasound examinations also had subsequent ultrasound examinations at 32 weeks gestation. Fetal growth characteristics were compared between preterm (less than 37 weeks gestation) and term deliveries, and among preterm deliveries with medical or obstetric indications, premature rupture of membranes (PROM), and spontaneous preterm labor. Results Forty-six infants (15.9%) were born preterm. At 32 weeks gestation, all fetuses later delivered preterm were already smaller than fetuses later delivered at term (P < .05) for all dimensions: head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and femur length (FL). However, after stratifying by cause of preterm delivery for those fetuses later delivered for medical or obstetric indications, we found that only AC was decreased (P < .01) and that the HC-AC ratio was elevated (asymmetric FGR). Neonates delivered after unsuccessfully treated PROM or preterm labor were symmetrically smaller in all characteristics (HC, AC, BPD, and FL). Conclusion By 32 weeks gestation, fetuses later delivered preterm are already significantly smaller than fetuses later delivered at term. However, when stratified by the etiology of preterm delivery, infants delivered preterm for medical or obstetric indications had asymmetric growth patterns, which suggests a growth failure late in pregnancy. Infants delivered preterm after PROM or after failed or no tocolysis for spontaneous preterm labor were proportionately smaller, implying an overall slowing of growth that may originate early in pregnancy and possibly demonstrate a more chronic stress.

Cervical length measurement by translabial sonography in women with preterm premature rupture of membranes: Can it be used to predict the latency period or peripartum maternal infection?

Objectives.u2003To determine the relationship between the translabial cervical length and the latency period or peripartum maternal infection in women with preterm premature rupture of membranes (PPROM). Methods.u2003Fifty-five women with a singleton gestation and PPROM between 24 and 34 weeks who had a translabial ultrasound performed within 24 hours of membrane rupture were included in the study. Translabial sonography was performed to assess cervical length and funneling. Ultrasound results were not made available to the managing obstetricians. Results.u2003The mean gestational age at PPROM in our cohort was 29.7 ± 2.8 weeks. The mean translabial cervical length was 2.8 ± 1.1 cm, and the median latency period was 10 days (interquartile range 4–15 days). There was no statistically significant correlation between cervical length and latency period (r = 0.15, p = 0.28). Additionally, latency periods less than seven days were not associated with cervical length cutoffs of 2.5 cm or 1.5 cm, or the presence of cervical funneling. Similarly, none of these criteria were associated with the development of either chorioamnionitis or postpartum endometritis. Conclusions.u2003Cervical length by translabial sonography was not associated with duration of the latency period or peripartum maternal infection in women with PPROM.

The impact of chorionicity on umbilical cord acid–base values in twin gestations

Objective: To evaluate the impact of chorionicity on inter-twin differences in acid–base status at birth. Methods: Records for twin pregnancies delivered at ⩾u200a24 weeks gestation from 1 January 1990 to 31 June 2000 were reviewed. Collected data included maternal demographics, gestational age, fetal presentation, anesthesia, delivery mode, inter-twin interval, umbilical artery (UA) and venous (UV) acid–base values, Apgar scores and birth weights. The influence of chorionicity on umbilical cord biochemistry was evaluated. (pu200a<u200a0.05 was considered significant.) Results: Analysis was carried out in 87 twin pairs (29 monochorionic, MC; and 58 dichorionic, DC). MC and DC twins were similar in maternal age (25.5 vs. 28.2 years), estimated gestational age (33.7 vs. 33.6 weeks), Cesarean delivery (55.2 vs. 52.6%), delivery interval (10 v s.5u2009min) and respective birth weights (twin A,1882 vs. 1981; and twin B,1828 vs. 1872u2009g). MC first twins had a higher UA pH (7.31u200a±u200a0.05 vs. 7.26u200a±u200a0.08; pu200a=u200a0.0005) than DC first twins. MC first and second twins had higher UA and UV bicarbonate levels than their DC counterparts (ΔpHu200a=u200a21.7u200a±u200a5.1 vs. 18.5u200a±u200a3.1u2009mmol/l and 22.0u200a±u200a3.5 vs. 19.6u200a±u200a2.5u2009mmol/l, respectively; pu200a=u200a0.003). MC twins were more discordant in UA pH than DC twins (ΔpHu200a=u200a0.043u200a±u200a0.09 vs. 0.003u200a±u200a0.07; pu200a=u200a0.009). MC and DC twins had a similar venous pH (ΔpHu200a=u200a0.01u200a±u200a0.06 vs. 0.02u200a±u200a0.06; pu200a=u200a0.5). Conclusions: There is a significant association between placental chorionicity and umbilical cord biochemistry in twins. Although it is possible that the mechanism of this finding is related to placental angioarchitecture, it is unlikely to be a result of simple mixing of blood volumes between twins. The physiology of underlying processes requires further study.

Cervical dilatation thresholds for initiation of group B streptococcus antibiotic prophylaxis for women with spontaneous preterm labor

Abstract Objective: To determine the optimal time for initiating group B streptococcus (GBS) antibiotic prophylaxis for women in spontaneous preterm labor. Methods: In total, 227 women delivering singleton infants after presenting with spontaneous preterm labor and intact membranes at 24 0/7–36 6/7 weeks were evaluated, as well as 150 undelivered women with threatened preterm labor during the same time period. The date and time of each cervical examination throughout labor were recorded. We calculated the percentages who would have correctly received at least 4u2009h of GBS prophylaxis if antibiotics were routinely initiated for various cervical dilatation thresholds during labor, as well as the percentage of undelivered women who would have received unnecessary antibiotic exposure at each cervical dilatation cutoff. Results: Delaying antibiotics until cervical dilatation reached 2u2009cm or greater would have resulted in 62.1% receiving four or more hours of antibiotics, compared to 66.5% if antibiotics were started on all women at admission (pu2009=u20090.33), while significantly reducing unnecessary antibiotic exposure in undelivered women from 100% to 62.0% (pu2009<u20090.001). The 2-cm threshold was applicable regardless of gestational age period or prior vaginal deliveryu2009≥u200920 weeks. Conclusions: GBS antibiotic prophylaxis may reasonably be withheld for women with suspected preterm labor until the cervix reaches 2u2009cm or greater at any time during labor.