Vaginal birth after Cesarean rates are declining rapidly in the rural state of Maine.

OBJECTIVE: The American College of Obstetricians and Gynecologists (ACOG) revised its practice bulletin on vaginal birth after Cesarean (VBAC) in October 1998 and July 1999 to require the presence of a surgeon, anesthesiologist and operating personnel throughout the trial of labor for patients with prior Cesarean. This study measures the change in VBAC rates from 1998 to 2001 and examines possible reasons for this change. STUDY DESIGN: We examined birth certificate and hospital data in the State of Maine from 1998 to 2001. Hospital-specific rates for primary Cesareans, total Cesareans, repeat Cesareans and vaginal deliveries after previous Cesarean were obtained. Additionally, we surveyed current obstetric-care providers in Maine regarding reasons for change in VBAC rates at their institutions. RESULTS: VBAC rates declined by over 50% from 30.1 to 13.1%. The total Cesarean rate climbed from 19.4 to 24.0%. The most commonly reported reason for decrease in VBAC varied depending on whether a practitioner's hospital met ACOG guidelines. CONCLUSION: A marked decline in VBAC occurred after the change in ACOG vaginal birth after Cesarean policy. Multiple factors have contributed to this decline, including patients refusing VBAC after counseling and inability of institutions to meet ACOG guidelines.

Role of ultrasound for Down syndrome screening in advanced maternal age.

OBJECTIVE: To determine the sensitivity and false-positive rate of Down syndrome screening by use of maternal serum screen and the genetic sonogram in women > or =35 years of age. STUDY DESIGN: We searched our perinatal databases retrospectively from January 1992 to January 2000 for the following criteria: known Down syndrome fetus or newborn, advanced maternal age, and genetic sonogram from 14-24 weeks' gestation. The a priori maternal age or maternal serum screen risk was modified by likelihood ratios for ultrasound markers. Without markers the risk was reduced by 50%. The cut-off was 1:270. RESULTS: Age and maternal serum screen had a sensitivity of 90.5% and a false-positive rate of 27.1%. Age and ultrasound had a 95.2% sensitivity and 43.5% false-positive rate, whereas the combination of age, maternal serum screen, and ultrasound had a 97.6% sensitivity and a 22.0% false-positive rate. CONCLUSION: The combination of age, maternal serum screen, and ultrasound improves the sensitivity for Down syndrome detection in the advanced maternal age population.

Hepatic vascular calcification: an early second trimester sonographic feature of idiopathic infantile arterial calcinosis.

Prenatal sonographic diagnosis of idiopathic infantile arterial calcinosis has been limited to the third trimester. We report a monozygotic twin gestation for which an 18-week ultrasound detected the unique finding of hepatic vascular calcification as the earliest feature of the disorder. In contrast to previous reports, second-trimester ultrasound may permit timely diagnosis of idiopathic infantile arterial calcinosis.

DNA diagnosis and management of Hermansky-Pudlak syndrome in pregnancy.

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism (OCA), platelet storage pool deficiency, and ceroid lipofuscin deposition. Sequelae including pulmonary fibrosis, colitis, and hemorrhagic diathesis can impact obstetric management. An 18-year-old primigravida with OCA was diagnosed during pregnancy with Hermansky-Pudlak syndrome by DNA analysis. Uneventful vaginal delivery occurred at term following prophylactic platelet transfusion. Women of northwestern Puerto Rican descent with OCA should be offered testing for HPS. Identification of affected individuals may permit optimal obstetric management.

Interpregnancy interval as a risk factor for placenta accreta.

OBJECTIVE: To determine if the interval from a previous delivery or cesarean to the next conception differs between patients with abnormally adherent placentas as compared to those with normally implanted placentas. METHODS: We identified all histologically confirmed placentas--accreta, increta, and percreta--at our hospital from 1992-1999. Subjects were excluded for primigravidity in the affected pregnancy or inability to identify matched controls. Cases were matched to the next three consecutive women delivering for maternal age (> or = 35 years or < 35 years), placenta previa (yes or no), prior cesarean (yes or no), prior uterine curettage (yes or no), and prior vaginal delivery (yes or no). The primary outcomes were delivery-to-conception and cesarean-to-conception intervals. Secondary outcomes included measures of maternal and neonatal morbidity. RESULTS: Delivery-to-conception intervals for cases and controls were 37.1 +/- 18.7 months and 37.9 +/- 22.7 months, respectively (P = .91). Cesarean-to-conception intervals for cases and controls were 35.2 +/- 18.2 and 48.1 +/- 31.0 months, respectively (P = .35). Cases were more likely to require uterine curettage (54.5 vs 0%), hysterectomy (81.8 vs 0%), and transfusion (72.7 vs 0%), all P < .001. Subjects with accreta delivered earlier (31.7 +/- 9.4 vs 38.1 +/- 2.6 weeks, P = .054) and smaller infants (2,158 +/- 1,180 g vs 3,159 +/- 781 g, P = .006) who were more likely to have five-minute Apgar scores < 7 (18.2% vs 0%, P = .038). CONCLUSIONS: Cesarean-to-conception intervals but not delivery-to-conception intervals are shorter in patients with abnormally adherent placentas. Placenta accreta is associated with significant maternal and perinatal morbidity.

A preliminary study of sonographic grading of fetal intracardiac echogenic foci: feasibility, reliability and association with aneuploidy.

OBJECTIVES: To prospectively and quantitatively grade intracardiac echogenic focus/foci (ICEF) using sonographic gain reduction and to determine the association of ICEF by grade with fetal aneuploidy. METHODS: Women referred for raised maternal age (> or = 35 years), or > 18 years of age and with a Down syndrome risk > or = 1/270, increased trisomy 18 risk by second trimester serum screen or a prior aneuploid offspring were included in this institutionally approved protocol. Only pregnancies of gestational age between 14 and 24 weeks were included. All women had a targeted ultrasound and were offered fetal chromosome analysis. The classification of ICEF was made from a four-chamber view of the fetal heart. The echo amplitude of the ICEF was compared to that of the thoracic spine and categorized according to the comparative gain setting at which the image of the relevant structure disappeared: Grade O = no ICEF present, Grade 1 = ICEF image lost before thoracic spine when gain was reduced, Grade 2 = ICEF image lost at same gain setting as thoracic spine, Grade 3 = thoracic spine image lost before ICEF. The primary outcome was a prenatally or post-natally detected chromosomal abnormality. RESULTS: A total of 885 eligible women were examined during the 21-month study period. ICEF were seen in 29 (3.3%) fetuses: 24(83%) in the left ventricle and five (17%) in the right ventricle. A chromosome abnormality was identified in 13/671 (1.9%) fetuses without ICEF (Grade 0) and 0/21 (0%) fetuses with Grade 1 ICEF. In contrast, two of five (40%) fetuses with Grade 2 ICEF were aneuploid (P = 0.005). No Grade 3 ICEF were observed. Additional sonographic abnormalities were seen in both aneuploid fetuses with Grade 2 ICEF. Interobserver agreement on ICEF grading was noted in 50/50 (100%) examinations (kappa = 1.0). CONCLUSIONS: Sonographic grading of ICEF is feasible and highly reliable. Grade 2 ICEF, especially when accompanied by additional sonographic markers of a chromosomal abnormality, are associated with aneuploidy significantly more frequently than Grade 1 ICEF.

Efficacy of community-based second trimester genetic ultrasonography in detecting the chromosomally abnormal fetus.

We sought to assess prospectively the efficacy of community-based genetic ultrasonography in detecting chromosomally abnormal fetuses in a high-risk population and determine independent markers of aneuploidy. Patients 18 years old and older who were between 14 and 24 weeks' gestation were included if referred for maternal age greater than 35 years, increased risk of Down syndrome or trisomy 18 by second trimester serum screen, or prior affected offspring. All women had a targeted ultrasonographic examination between April 1997 and June 1999 and were offered fetal chromosomal analysis. Markers of aneuploidy and pregnancy outcomes were recorded prospectively. The primary outcome was prenatally or postnatally detected chromosomal abnormalities. Of the 1030 fetuses seen during the study, 789 had outcome data available and constituted the study group. In this group, 694 (87.9%) ultrasonograms were normal, 73 (9.2%) had one marker present, 17 (2.2%) had two markers present, and 5 (0.6%) had three or more markers present. Fourteen of 17 (82.3%) aneuploid fetuses had an abnormal ultrasonogram (one or more markers present), including 5 of 7 (71.4%) with Down syndrome. Logistic regression showed abnormal four-chamber view, structural anomaly, and intracardiac echogenic focus to be significant aneuploidy markers. The amniocentesis rate was 334 of 1030 (32.4%), and it increased with the number of sonographic markers noted (0 = 29.9%, 1 = 60.2%, 2 = 70.6%, 3 or more = 80%). Genetic ultrasonography is highly effective in identifying chromosomally abnormal fetuses in a community-based practice.

Obesity-related complications of pregnancy vary by race.

OBJECTIVE: To evaluate racial effects on obstetric complications in obese gravidas. METHODS: The obstetric database was reviewed for the period 6/1/94 to 3/31/97. All clinic patients delivering singletons were included. Obesity was defined as a body mass index (BMI) of 29 kg/m2 or more, or a pre-pregnancy weight of 200 pounds or more. Complications studied included hypertension, diabetes, cesarean delivery, and fetal macrosomia. RESULTS: Of 2,424 eligible subjects, 168 were obese (6.9%). Obese patients had higher rates of chronic hypertension and pregestational diabetes, as well as increased rates of preeclampsia, gestational diabetes, fetal macrosomia, cesarean delivery, and operative vaginal delivery compared to nonobese patients. Of the obese patients, 105 (63%) were Hispanic, 39 (23%) were African American, and 24 (14%) were White; no Asian or Mixed/Other patients were obese. Mean BMIs of the obese subgroups did not differ (P = 0.14), but prepregnancy weights were greater in Whites than Hispanics (P < 0.002). Obese Hispanics had an increased rate of gestational diabetes (P = 0.04) and of infant weight > or =4,500 g (P =.03). Obese Hispanic and African American women were more likely than obese Whites to deliver by cesarean (P = 0.03). CONCLUSION: Racial differences affect the complication rates in obese gravidas, and may influence prenatal counseling and pregnancy management.

Labor and delivery following successful external cephalic version.

The objective of this study is to determine if successful external cephalic version is followed by an increased likelihood of prolonged labor or operative delivery. Women having a successful external cephalic version of a normal singleton fetus > or =37 weeks' gestation between January 1, 1997 and December 31, 1998 were included. Each case was matched for gestational age at delivery (+/-1 week), labor onset (spontaneous or induced), prior vaginal delivery (yes or no), and cervical dilation on admission for delivery (+/-1 cm) to the next three patients delivering a spontaneously vertex term singleton. Maternal demographics, intrapartum variables, neonatal outcomes, and route of delivery were examined. Statistical comparisons were performed by the Student's t-test or Fisher's exact test. The 38 cases and 114 controls were similar by maternal age, race, gestational age at delivery, birth weight, and insurer. There were no differences in the frequency of epidural or oxytocin use, maternal genital tract lacerations, or blood loss at delivery. Neonatal outcomes, assessed by 1- and 5-min Apgar score <7, or neonatal intensive care unit (NICU) admission did not differ between cases and controls. The labor length of patients undergoing successful version was similar to that of women laboring with spontaneously vertex fetuses (10.8 +/- 8.9 vs. 10.1 +/- 10.1 hr, p = 0.4). The frequencies of operative vaginal and cesarean delivery in cases did not differ from those of controls (3/38 vs. 1/114, p = 0.56 and 4/38 vs. 8/114, p = 0.51, respectively.) Labor duration and delivery route following successful external cephalic version do not differ from women with spontaneously vertex fetuses.

Unexplained elevated midtrimester maternal serum levels of alpha fetoprotein, human chorionic gonadotropin, or low unconjugated estriol: recurrence risk and association with adverse perinatal outcome.

OBJECTIVE: To determine if women experiencing an unexplained elevated maternal serum alpha fetoprotein (MSAFP; > or =2.0 MoM) or human chorionic gonadotropin (hCG; > or =2.0 MoM), or low unconjugated estriol (E3; < or =0.5 MoM) in one pregnancy are at increased risk for similar results in a subsequent pregnancy, and to determine if recurrence of these analyte extremes is associated with adverse perinatal outcome. METHODS: We identified all women delivering two consecutive singleton pregnancies at one hospital between 1992-1997 for whom second trimester trisomy 21 serum screen was performed in each pregnancy. All screens were performed in a single laboratory. Each pregnancy delivered after 20 weeks and had gestational age confirmed by ultrasound prior to 24 weeks. Subjects were excluded if a fetal anomaly or aneuploidy was present. Adverse outcomes included abruption, oligohydramnios, preeclampsia, preterm membrane rupture, preterm delivery, stillbirth, birthweight <10th centile, and admission to neonatal intensive care unit (NICU). RESULTS: A total of 538 women had 1,076 pregnancies meeting inclusion criteria; 12/515 (2.3%) of women with a normal MSAFP, 28/470 (6.0%) with a normal hCG, and 11/504 (2.2%) with a normal E3 in the first pregnancy had an anomalous result for the respective analyte in the second pregnancy. In contrast, only 4/23 (17.4%) patients with an elevated MSAFP (P = 0.003), 14/44 (31.8%) with an elevated hCG (P < 0.001), and 2/10 (20.0%) with a low E3 (P < 0.025) in the first pregnancy had the same analyte anomaly recur in the second pregnancy. The odds ratios for recurrent elevated MSAFP, hCG, and low E3 were 7.5, 5.3, and 9.2, respectively. Adverse perinatal outcomes occurred with similar frequency, regardless of MSAFP, hCG, or E3 results in consecutive pregnancies, using women with normal MSAFP, hCG, and E3 results in one or both pregnancies as controls. CONCLUSIONS: Women experiencing an anomalous serum analyte in one pregnancy are at significant risk to experience the same analyte result in a subsequent pregnancy.

Fetal intracardiac echogenic foci: current understanding and clinical significance.

The detection of fetal intracardiac echogenic foci (ICEF) by ultrasound was first reported in 1987. Despite many investigations, the relationship of ICEF with congenital heart malformations and chromosomal abnormalities remains unclear. This review describes the current understanding of ICEF based on a literature search from 1980 to the present. ICEF are observed in 0.5 to 20 percent of fetuses, with an overall frequency of 5.6 percent. These small, discrete structures near the papillary muscles and chordae tendinae move in synchrony with the intraventricular valves. They likely represent microcalcification of the papillary muscles. ICEF are most commonly seen in the left ventricle and occasionally in the right ventricle or bilaterally. Intra-atrial or diffuse ICEF are rare. In the chromosomally normal fetus, ICEF are not associated with congenital heart defects. The presence of ICEF in fetuses at high risk for chromosomal abnormalities suggests an increased possibility of aneuploidy, especially if other sonographic markers are noted. A similar association is observed with trisomy 21 in particular. The significance of ICEF in fetuses at low risk for aneuploidy is less clear and represents an area for future research.

Twin vaginal birth after cesarean.

OBJECTIVE: To determine both success rate and maternal-fetal outcome of vaginal birth after cesarean in twin gestations. METHODS: We identified all women from a single center attempting vaginal birth of twins after cesarean from 1988-98. Twin pairs were excluded for delivery < or = 25 weeks gestation, monoamnionicity, nonvertex twin A, or major anomaly or death of either twin. Cases were matched to the next three consecutive twin gestations attempting vaginal delivery without a prior cesarean. Variables matched were gestational age at delivery (+/- 1 week), presentations of both fetuses, labor onset (spontaneous or induced), and prior vaginal delivery (yes or no). The primary outcome was successful vaginal delivery of both fetuses. Secondary maternal outcomes included chorioamnionitis, hemorrhage requiring transfusion, hysterectomy, uterine rupture, and length of stay. Neonatal outcomes included one and five minute Apgars, NICU admission, and length of NICU stay. RESULTS: Twelve parturients were matched to 36 controls. There were no differences between the groups with respect to maternal demographics, intrapartum variables, fetal genders, birthweights, or chorionicity. Women with a prior cesarean (10/12) delivered both twins vaginally compared to 31/36 parturients without a prior cesarean (P = 1.0). There were no differences between cases and controls with respect to maternal morbidity (1/12 vs 4/36, P = 1.0), or postpartum stay (2.5 +/- 1.0 vs 2.5 +/- 2.3 days, P = .25). Neonatal outcomes were similar by birth order, except that second-born twins of cases had significantly longer NICU stays than controls (22.7 +/- 3.8 vs 10.4 +/- 7.8 days, P = .04). CONCLUSION: Twin trial of labor after cesarean is associated with a high success rate of vaginal delivery but may be associated with a more lengthy NICU stay for the second twin.

Intentional iron overdose in pregnancy--management and outcome.

The objectives of our study were to 1) determine if peak maternal serum iron level or toxicity stage after intentional overdose is associated with adverse maternal-fetal outcome, and 2) describe the use of deferoxamine antidote therapy in obstetric patients. A computer search of the English language literature from 1966-1998 used the key words iron toxicity, iron poisoning, deferoxamine, and pregnancy to identify peer-reviewed papers reporting intentional iron overdoses in pregnancy. Two investigators independently extracted data from articles and their references including stage of toxicity (0 = asymptomatic, 1 = gastrointestinal symptoms, 2 = metabolic disturbance, 3 = organ failure), with differences resolved by consensus. Statistical analysis used the Student t-test, Fisher exact test, or ANOVA, as appropriate. Fourteen publications were identified, describing 61 cases of obstetric iron overdose, including one recent case at our institution. Compared with women who had lower peak levels, women with peak serum iron levels > or =400 mcg/dL were more frequently symptomatic (12/13 vs. 5/10, respectively, p = 0.05). Peak iron level > or =400 mcg/dL was not associated with increased risk of spontaneous abortion, preterm delivery, congenital anomalies, or maternal death. However, patients with stage 3 toxicity were more likely to spontaneously abort (1/3 vs. 1/56, respectively), deliver preterm (2/3 vs. 6/56, respectively), or experience maternal death (3/3 vs. 0/56, respectively). The proportions of patients treated with deferoxamine and total dosages of deferoxamine were similar by peak iron level (> or =400 vs. <400 mcg/dL) and toxicity stage (0-3). Peak iron levels > or =400 mcg/dL are associated with symptomatic iron overdose. Stage 3 toxicity is associated with spontaneous abortion, preterm delivery, and maternal death.

Prenatally diagnosed sacrococcygeal teratoma: a unique expression of trisomy 1q.

Partial duplication of the long arm of chromosome 1 has been observed in fetal intracranial teratomas. We sonographically diagnosed a 19-week fetus with sacrococcygeal teratoma, cerebral ventriculomegaly, and cerebellar hypoplasia. Chromosomal analysis of amniocytes showed an unbalanced translocation between chromosomes 1 and 15, resulting in trisomy 1q21-->1 qter. Duplication or over expression at more than one locus on the long arm of chromosome 1 may be required for the development of an extra-gonadal teratoma.

Meralgia paresthetica: an unusual complication of post-cesarean analgesia.

Intramuscular (IM) injections may be associated with nerve injury, classically the sciatic nerve after intragluteal injection. We describe an unusual injury of the lateral femoral cutaneous nerve following an IM injection of 100 mg meperidine and 25 mg promethazine in the anterolateral right thigh. Although the thigh is advocated as a relatively safe site for IM injection, iatrogenic neuropathy may result. Awareness of the anatomy of the lateral femoral cutaneous nerve and avoiding injections into a partially anesthetized extremity may decrease the likelihood of recurrences.

Ultrasonographic diagnosis of thoracopagus conjoined twins in a monoamniotic triplet gestation.

Ultrasonographic examination at 16 weeks 5 days' gestation diagnosed a monoamniotic triplet gestation complicated by thoracopagus conjoined twins. After pregnancy termination, the ultrasonographic diagnoses were confirmed by pathologic examination. In reporting the first ultrasonographically diagnosed monamniotic triplets with conjoined twins, we demonstrate that a systematic evaluation by twin-derived ultrasonographic techniques may permit correct diagnosis of unusual triplet pregnancies.

Correlation of maternal and fetal hepatitis B antibody titers following maternal vaccination in pregnancy.

The objective of this study was to compare the levels of hepatitis B antibody in maternal and cord blood following maternal vaccination in pregnancy and to determine the level of maternal hepatitis B surface antibody (HbsAb) associated with a seroprotective level in cord blood. Thirty-seven (37) healthy gravidas who were identified as seronegative for hepatitis B surface antigen (HbsAg) and antibody (HbsAb) on initial prenatal assessment and subsequently began a series of three vaccinations in the pregnancy with hepatitis B recombinant DNA vaccine (Engerix-B, SmithKline Beecham) were studied. These mothers represented the first group of gravidas delivering between 6/1/97 and 8/1/97 following the iniatiation of a new protocol of offering hepatitis B vaccination to all patients testing seronegative to HbsAg and HbsAb. All gravidas were given a dose of 20 microg into the deltoid muscle utilizing a 1 1/2-inch needle at a schedule of 0, 1, and 6 months. At the time of delivery specimens were obtained for maternal serum levels and paired cord blood levels of HbsAb. Levels were determined utilizing a quantitative enzyme-linked immunoadsorbent assay (ELISA) analysis (AUSAB-EIA Abbott Lab; Abbott Park, IL). A serum titer of > or =10 mLU/mL was considered seroprotective. Maternal and cord blood groups identified by seroprotection status were then sudivided by number of maternal vaccines received. Data were compared using the Student's t-test and Chi-square or Fisher's exact test. Eighteen gravidas (49%) had seroprotective titers at the time of delivery. Of these, 16 (88%) had seroprotective cord blood levels. All maternal specimens with a HbsAb titer > or =35 mLU/mL were associated with cord blood tiers > or =10 mLU/mL. When maternal titers achieved seroprotective levels of HbsAb, there was no difference in the frequency of cord blood seroprotection comparing groups by number of maternal vaccine doses received. When maternal titers of HbsAb achieve seroprotective levels following vaccination, cord blood seroprotection was achieved in 88% of studied patients. Maternal HbsAb titers > or =35 mLU/mL were associated with cord blood seroprotective levels in all cases.

Neonatal morbidity at 34-37 weeks: the role of ruptured membranes.

OBJECTIVE: Evaluate neonatal morbidity in deliveries occurring between 34 0/7 and 36 6/7 weeks' gestation, comparing outcomes in pregnancies complicated by preterm premature rupture of membranes with those in which delivery occurred with intact membranes prior to the onset of labor. METHODS: The obstetric database was reviewed for a 5-year period. Healthy gravidas delivering nonanomalous singleton gestations from vertex presentations were evaluated, with corticosteroid or antibiotic administration or both noted. The neonatal database was reviewed for the following complications: admission to the neonatal intensive care unit, need for assisted ventilation, and development of hyaline membrane disease, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, or culture-proven sepsis. Groups were compared using chi2 tests. The power of this study to detect a ten-fold decrease in the likelihood of neonatal complications at the P<.05 significance level was greater than 90%. RESULTS: Of 853 eligible pregnancies, 414 (48.5%) gravidas had ruptured membranes prior to the onset of active labor. No difference existed between groups in the number of patients who had received corticosteroids during pregnancy, but patients with ruptured membranes were more likely to have received antibiotics prior to delivery. No neonatal deaths occurred, and neonatal morbidity was low in both groups. CONCLUSION: No clinically significant difference exists in neonatal outcome between 34 0/7 and 36 6/7 weeks' gestation as the result of membrane status prior to the onset of labor.

Hepatitis B vaccination in pregnancy: factors influencing efficacy.

OBJECTIVE: To determine seroprotective antibody response after hepatitis B vaccination during pregnancy and to assess factors influencing the rate of maternal seroprotection. METHODS: Records of 80 healthy gravidas who elected hepatitis B vaccination during pregnancy, after being identified as hepatitis B surface antigen (HbsAg) and antibody (HbsAb) negative on initial prenatal screen, were analyzed retrospectively. Each gravida was begun on a series of three recombinant hepatitis B vaccines at 0, 1, and 6 months. At 36-40 weeks' gestation, all gravidas were rescreened for seroprotective levels of HbsAb using qualitative enzyme-linked immunosorbent assay analysis. The women were grouped by maternal age (less than 25 years or at least 25 years), smoking history, maternal weight, body mass index (BMI) (less than 30, at least 30, less than 34, or at least 34), number of vaccinations received, race-ethnicity, gestational age at vaccination, and vaccination-to-rescreening interval. Data were compared by t test, chi2 test, or Fisher exact test. Stepwise logistic regression analysis was done. RESULTS: At rescreening, 39 (49%) of the 80 women had seroprotective HbsAb conversion. After two vaccinations, obese women (BMI at least 30) (P = .04), women at least 25 years old (P = .04), and women with smoking histories (P = .005) were significantly less likely to respond to the vaccine. Logistic regression analysis for predicting failure of seroprotective response after two vaccinations showed significantly increased odds for severe obesity with BMI at least 34 (odds ratio [OR] 16.2; 95% confidence interval [CI] 1.7, 154.7), smoking history (OR 7.5; 95% CI 2.0, 27.7), and age at least 25 years (OR 3.9; 95% CI 1.1, 14.4). CONCLUSION: Maternal obesity, advancing age, and smoking have negative influences on the efficacy of hepatitis B vaccination in pregnant women.