Ellice Lieberman

Low birthweight at term and the timing of fetal exposure to maternal smoking.

OBJECTIVES This study was undertaken to evaluate the risk of small-for-gestational-age birth for women who stop smoking or begin to smoke during pregnancy. METHODS Women with term singleton pregnancies from a hospital-based cohort of 11,177 were classified as (1) nonsmokers; (2) smoked throughout pregnancy; (3) smoked during first trimester only; (4) smoked during first and second trimesters only; and (5) smoked during second and third trimesters or during third trimester only. Risk of small-for-gestational-age birth according to smoking category was estimated and adjusted for confounding factors by logistic regression. RESULTS Women who stopped smoking by the third trimester were not at increased risk of small-for-gestational-age birth compared with nonsmokers. Women who began smoking during the second or third trimester had an elevated risk of small-for-gestational-age birth (odds ratio [OR] = 1.83; 95% confidence interval [CI] = 1.25, 2.67) similar to that for women who smoked throughout pregnancy (OR = 2.20; 95% CI = 1.90, 2.54). Risk of small-for-gestational-age birth increased with the number of cigarettes smoked during the third trimester. CONCLUSIONS It is during the third trimester that smoking retards fetal growth, presenting a compelling opportunity for smoking cessation interventions. Programs must emphasize the importance of not resuming smoking late in pregnancy.

Unintended effects of epidural analgesia during labor: A systematic review

Epidural analgesia is used by more than half of laboring women, yet there is no consensus about what unintended effects it causes. To evaluate the state of our knowledge, we performed a systematic review of the literature examining the unintended maternal, fetal, and neonatal effects of epidural analgesia used for pain relief in labor by low-risk women. Our review included randomized and observational studies appearing in peer review journals since 1980. Much of the evidence is equivocal. Existing randomized trials are either small or do not allow clear interpretation of the data because of problems with protocol compliance. In addition, few observational studies control for the confounding factors that result because women who request epidural are different from women who do not. There is considerable variation in the association of epidural with some outcomes, particularly those that are heavily practice-based. Despite this variation, there is sufficient evidence to conclude that epidural is associated with a lower rate of spontaneous vaginal delivery, a higher rate of instrumental vaginal delivery and longer labors, particularly in nulliparous women. Women receiving epidural are also more likely to have intrapartum fever and their infants are more likely to be evaluated and treated for suspected sepsis. There is insufficient evidence to determine whether epidural does or does not tend to increase the risk of cesarean delivery or fetal malposition. Adverse effects on the fetus may occur in the subset of women who are febrile. Women should be informed of unintended effects of epidural clearly supported by the evidence, especially since epidural use is almost always an elective procedure. Further research is needed to advance our understanding of the unintended effects of epidural. Improved information would permit women to make truly informed decisions about the use of pain relief during labor.

A comparison of risk factors for preterm labor and term small-for-gestational-age birth.

&NA; This study estimates the effects of 23 factors on the prevalence of premature labor and fetal growth retardation across the entire birthweight spectrum. We studied risk factors for premature labor within the domain of babies of appropriate size for their gestational age (N = 9,490). We also studied risk factors for fetal growth retardation among babies born at term (N = 10,889). Preterm labor was associated independently with young maternal age, low prepregnant weight, low weekly weight gain, nulliparity, previous preterm birth, histories of two or more induced abortions, spontaneous abortions, or stillbirths, uterine exposure to diethylstilbestrol (DES), incompetent cervix, uterine anomaly, and pyelonephritis. Odds ratios ranged from 1.7 to 5.9. Fetal growth retardation, as estimated by small‐for‐gestational‐age birth, was associated independently with black race, young maternal age, short maternal height, low prepregnancy weight, low weekly weight gain, and smoking, as well as nulliparity, previous preterm birth, three or more abortions, uterine anomaly, and uterine exposure to DES. Odds ratios ranged from 1.6 to 2.8. Our study shows the importance for etiologic understanding of separating diverse routes to low birthweight and considering the occurrence of adverse pregnancy outcomes along the entire birthweight spectrum. The findings reinforce the need for comprehensive control of confounding in studies of pregnancy outcome.

The Role of Lifestyle in Preventing Low Birth Weight

Lifestyle behaviors such as cigarette smoking, weight gain during pregnancy, and use of other drugs play an important role in determining fetal growth. The relationship between lifestyle risk factors and low birth weight is complex and is affected by psychosocial, economic, and biological factors. Cigarette smoking is the largest known risk factor for low birth weight. Approximately 20% of all low birth weight could be avoided if women did not smoke during pregnancy. Reducing heavy use of alcohol and other drugs during pregnancy could also reduce the rate of low birth weight births. Pregnancy and the prospect of pregnancy provide an important window of opportunity to improve womens health and the health of children. The adoption before or during pregnancy of more healthful lifestyle behaviors, such as ceasing to smoke, eating an adequate diet and gaining enough weight during pregnancy, and ceasing heavy drug use, can positively affect the long-term health of women and the health of their infants. Detrimental lifestyles can be modified, but successful modification will require large-scale societal changes. In the United States, these societal changes should include a focus on preventive health, family-centered workplace policies, and changes in social norms.

The Genetic Sonogram A Method of Risk Assessment for Down Syndrome in the Second Trimester

Objective. To determine the risk of Down syndrome in fetuses with sonographic markers using the Bayes theorem and likelihood ratios. Methods. We prospectively evaluated the midtrimester sonographic features of fetuses with Down syndrome and compared them with euploid fetuses. Patients were referred for an increased risk of aneuploidy and evaluated for the presence of structural defects, a nuchal fold, short long bones, pyelectasis, an echogenic intracardiac focus, and hyperechoic bowel. All fetuses underwent amniocentesis at the time of sonographic assessment. The sensitivity, specificity, and likelihood ratios for markers were calculated both as nonisolated and isolated findings. Results. There were 164 fetuses with Down syndrome and 656 euploid fetuses. The presence of any marker resulted in sensitivity for the detection of Down syndrome of 80.5% with a false‐positive rate of 12.4%. The absence of any markers conferred a likelihood ratio of 0.2, decreasing the risk of Down syndrome by 80%. As an isolated marker, the nuchal fold had an “infinite” likelihood ratio for Down syndrome; a short humerus had a likelihood ratio of 5.8, whereas structural anomalies had a likelihood ratio of 3.3. Other isolated markers had low likelihood ratios because of the higher prevalence in the unaffected population. The likelihood ratios for the presence of 1, 2, and 3 of any of the markers were 1.9, 6.2, and 80, respectively. Conclusions. Although an isolated marker with a low likelihood ratio may not increase a patients risk of Down syndrome, the presence of such a marker precludes reducing the risk of aneuploidy. Clusters of markers appear to confer a higher risk.

Persistent fetal occiput posterior position: obstetric outcomes.

OBJECTIVE To evaluate the obstetric outcomes associated with persistent occiput posterior position of the fetal head in term laboring patients. METHODS We performed a cohort study of 6434 consecutive, term, vertex, laboring nulliparous and multiparous patients, comparing those who delivered infants in the occiput posterior position with those who delivered in the occiput anterior position. We examined maternal demographics, labor and delivery characteristics, and maternal and neonatal outcomes. RESULTS The prevalence of persistent occiput posterior position at delivery was 5.5% overall, 7.2% in nulliparas, and 4.0% in multiparas (P < .001). Persistent occiput posterior position was associated with shorter maternal stature and prior cesarean delivery. During labor and delivery, the occiput posterior position was associated with prolonged first and second stages of labor, oxytocin augmentation, use of epidural analgesia, chorioamnionitis, assisted vaginal delivery, third and fourth degree perineal lacerations, cesarean delivery, excessive blood loss, and postpartum infection. Newborns had lower 1-minute Apgar scores, but showed no differences in 5-minute Apgar scores, gestational age, or birth weight. CONCLUSION Persistent occiput posterior position is associated with a higher rate of complications during labor and delivery. In our population, the chances that a laboring woman with persistent occiput posterior position will have a spontaneous vaginal delivery are only 26% for nulliparas and 57% for multiparas.

Association of epidural analgesia with cesarean delivery in nulliparas.

Objective To evaluate whether epidural analgesia during the first stage of labor is associated with an increased risk of cesarean delivery. Methods The association of epidural analgesia and cesarean delivery was examined in a retrospective study of 1733 low-risk, term nulliparas with singleton infants in vertex presentations, in which labor began spontaneously. To evaluate the effect of epidural analgesia on cesarean deliveries, independent of other factors influencing the use of epidural analgesia, we used propensity scores to create five subgroups (quintiles) of women who, based on characteristics discernible at admission, appeared equally likely to receive epidural analgesia. Multivariate logistic regression analysis was used to control for confounding. Results Overall, the cesarean rate among women receiving epidural analgesia was 17% (168 of 991), compared with 4% (30 of 742) among those who did not receive epidural analgesia. An increased cesarean rate among women receiving epidural analgesia was present in all propensity quintiles. In an adjusted logistic regression analysis, women receiving epidural analgesia were 3.7 times more likely to undergo a cesarean (95% confidence interval 2.4, 5.7). The greatest increase in cesarean risk was noted when epidural analgesia was administered earlier in labor, but there was a more than twofold increase regardless of the dilation and station at administration of epidural analgesia. Conclusions Epidural analgesia may increase substantially the risk of cesarean delivery. Although the causal nature of this association remains open to debate, prenatal care providers should routinely discuss the risks and benefits of epidural analgesia with women during their pregnancies so that they can make informed decisions about the use of pain relief during labor.

Rate of uterine rupture during a trial of labor in women with one or two prior cesarean deliveries

OBJECTIVE We sought to determine whether there is a difference in the rate of symptomatic uterine rupture after a trial of labor in women who have had 1 versus 2 prior cesarean deliveries. STUDY DESIGN The medical records of all women with a history of either 1 or 2 prior cesarean deliveries who elected to undergo a trial of labor during a 12-year period (July 1984-June 1996) at the Brigham and Womens Hospital were reviewed. Rates of uterine rupture were compared for these 2 groups. Potential confounding variables were controlled by using logistic regression analyses. RESULTS Women with 1 prior cesarean delivery (n = 3757) had a rate of uterine rupture of 0.8%, whereas women with 2 prior cesarean deliveries (n = 134) had a rate of uterine rupture of 3.7% (P =.001). In a logistic regression analysis that was controlled for maternal age, use of epidural analgesia, oxytocin induction, oxytocin augmentation, the use of prostaglandin E(2) gel, birth weight, gestational age, type of prior hysterotomy, year of trial of labor, and prior vaginal delivery, the odds ratio for uterine rupture in those patients with 2 prior cesarean deliveries was 4.8 (95% confidence interval, 1.8-13. 2) CONCLUSIONS Women with a history of 2 prior cesarean deliveries have an almost 5-fold greater risk of uterine rupture than those with only 1 prior cesarean delivery.

Interdelivery interval and risk of symptomatic uterine rupture

Objective To relate interdelivery interval to risk of uterine rupture during a trial of labor after prior cesarean delivery. Methods We reviewed the medical records of all women who had a trial of labor after cesarean delivery over 12 years (July 1984 to June 1996). Analysis was limited to women with only one prior cesarean delivery and no prior vaginal deliveries who delivered term singletons and whose medical records included the month and year of the prior delivery. The time in months between the prior cesarean delivery and the index trial of labor was calculated, and the women were divided accordingly to permit comparison with respect to symptomatic uterine rupture. Results Two thousand four hundred nine women had trials of labor after one prior cesarean delivery and had complete data from the medical records. There were 29 uterine ruptures (1.2%) in the population. For interdelivery intervals up to 18 months, the uterine rupture rate was 2.25% (seven of 311) compared with 1.05% (22 of 2098) with intervals of 19 months or longer (P = .07). Multiple logistic regression was used to assess the risk of uterine rupture according to interdelivery interval while controlling for maternal age, public assistance, length of labor, gestational age at least 41 weeks, and oxytocin use. Women with interdelivery intervals of up to 18 months were three times as likely (95% confidence interval, 1.2, 7.2) to have symptomatic uterine rupture. Conclusion Interdelivery intervals of up to 18 months were associated with increased risk of symptomatic uterine rupture during a trial of labor after cesarean delivery compared with that for longer interdelivery intervals.

Echogenic intracardiac focus: A sonographic sign for fetal down syndrome

Objective To determine whether an echogenic intracardiac focus identified in the second-trimester fetus is related to an increased risk of Down syndrome. Methods During a 10-month period, all women with singleton gestations who underwent second-trimester genetic amniocentesis for non-imaging indications were evaluated prospectively by prenatal sonography. The presence or absence of an echogenic intracardiac focus was noted. Karyotypic information was obtained on each fetus. Results Among the 1334 patients in the study group, 66 fetuses (4.9%) had an echogenic intracardiac focus. Four of 22 fetuses (18%) with trisomy 21 had an echogenic intracardiac focus, compared with 62 (4.7%) of 1312 fetuses without Down syndrome who also had an echogenic intracardiac focus (P = .004). Sonographic identification of an echogenic intracardiac focus was associated with a fourfold increased risk of Down syndrome (risk ratio 4.3, 95% confidence interval 1.5–12.3). The overall prevalence of Down syndrome in our study population was 1.6%. The sensitivity, specificity, and positive predictive value for using the presence of an echogenic intracardiac focus to identify a fetus with Down syndrome was 18.2, 95.3, and 6.1%, respectively. Extrapolating to a lower risk population, the positive predictive value of an echogenic intracardiac focus for detecting Down syndrome in patients at an age-based risk of one in 250, one in 500, and one in 1000 was calculated to be 1.53, 0.77, and 0.39% respectively. Conclusions Fetuses with an echogenic intracardiac focus have a significantly increased risk of Down syndrome. Although most fetuses with this finding are normal, patients carrying fetuses with an echogenic intracardiac focus should be counseled about the increased risk of trisomy 21.