Asaf Ferber

A functional definition of prolonged pregnancy based on daily fetal and neonatal mortality rates

The standard definition of ‘prolonged pregnancy’ is 42 completed weeks of gestation or more. This definition is based on statistical considerations and is sanctioned by the American College of Obstetricians and Gynecologists (ACOG), the World Health Organization (WHO), and the International Federation of Gynecology and Obstetrics (FIGO)1–3. However, multiple studies have shown that the risk of adverse perinatal outcome increases as gestation advances beyond 41 weeks of gestation or earlier4–7. Thus it is clear that the definition of the upper limit of a normal pregnancy is somewhat arbitrary and certainly imprecise. Traditionally, perinatal mortality has been calculated per 1000 births. Using this methodology and a large computerized database, we evaluated weekly fetal and neonatal mortality rates in 181 524 accurately dated term and post-term pregnancies6. A statistically significant increase in fetal mortality was detected from 41 weeks’ gestation onward. In contrast, the odds ratios for neonatal mortality did not demonstrate a significant increase as gestational age (GA) advanced beyond 40 weeks. In view of the large number of women who are undelivered by 41 or even 42 weeks’ gestation, the data indicating that perinatal mortality is increased in these pregnancies present a major public health dilemma. Several publications have questioned the traditional method used to calculate fetal mortality7–12. As stated by Smith7, ‘estimating the probability of an event requires that the number of events (numerator) be divided by the number of subjects at risk for that event (denominator)’. Therefore, it seems logical to calculate fetal mortality as fetal deaths per 1000 on-going pregnancies (rather than per 1000 deliveries), whereas the probability of neonatal mortality should be calculated as the number of neonatal deaths per 1000 live births. Caughey et al.13 recently reached a similar conclusion. Indeed, as early as 1987, Yudkin et al.8 argued that the risk of stillbirth would be better measured as ‘the number of impending stillbirths divided by the total number of undelivered fetuses’. With this measure and a database of 40 635 deliveries (1978–1985), the authors showed an exponential increase in the risk of stillbirth, from 0.3/1000 at 29 weeks’ gestation to 1.8/1000 at 41 weeks’ gestation. Hilder et al.10 reported similar results in 1998. In both of these studies the authors calculated the weekly risk of fetal demise conditional on fetal survival until that gestational week8,10. One should not, however, ignore the fact that the fetus is exposed to the risk of intrauterine demise not only during the week of delivery, but also during the period leading to the week of delivery. The traditional conditional probability for stillbirth at a given GA fails to take into account the risks of death in all the preceding weeks. Therefore, Smith7 recently applied life-table analysis techniques and calculated the ‘weekto-week’ cumulative probabilities of stillbirth. This risk increased from approximately 0.4/1000 at 37 weeks’ gestation to 11.5/1000 at 43 weeks’ gestation. It is intuitively clear that the rate of fetal death and the rate of neonatal death can be viewed as two independent phenomena acting in opposite directions. For example, early in the third trimester of pregnancy, the risk of neonatal death (per 1000 live births) is very high, while

Is severe macrosomia manifested at 11–14 weeks of gestation?

To determine the association between fetal biometry in the first or early second trimester and severe macrosomia at delivery.

The impact of maternal age, body mass index and maternal weight gain on the glucose challenge test in pregnancy

Objective. The aim of this study was to determine whether maternal age, prepregnancy and mid-trimester body mass index (BMI), or excessive mid-pregnancy weight gain predict abnormal glucose challenge test (GCT) results. Methods. A retrospective chart review of 75 consecutive singleton pregnancies was performed. Patients were screened at 24–28 weeks of gestation with a 50-g oral GCT. Prepregnancy BMI and pregnancy weight gain up to the time of GCT testing, as well as other demographic data, were recorded. Statistical analysis included regression analysis and Students t-test, receiver–operator characteristic curve and multivariate logistic regression. Results. Maternal age and prepregnancy and mid-trimester BMI were significantly higher in women with an abnormal GCT (p < 0.05). A direct correlation was found between these parameters and GCT results (R2 = 0.08, R2 = 0.102 and R2 = 0.116, respectively; p < 0.05). Mid-trimester maternal BMI of ≥30 kg/m2 and maternal age ≥32 years are the optimal predictors of abnormal GCT results. Conclusions. Mid-trimester maternal BMI of ≥30 kg/m2 and maternal age ≥32 years are useful predictors of abnormal GCT results. We suggest that these factors should also be considered when selective screening for gestational diabetes mellitus is practiced.

Doppler evaluation of the fetus

Doppler ultrasound is a noninvasive technique that is commonly used to evaluate maternal and fetal hemodynamics. This testing modality is based on the premise that an insufficient uterine, placental, or fetal circulation results in an adverse pregnancy outcome and that these abnormalities can be defined with the use of Doppler velocimetry. Doppler techniques have been used in obstetrics since the initial report of successful recording of blood flow signals from the umbilical artery by Fitzgerald and Drumm in 1977. Although Doppler velocimetry is the newest modality to assess fetal wellbeing, it has been the subject of more randomized controlled trials than any other test of fetal well-being.

Acute Progression of a Unilateral Fetal Ovarian Cyst to Complex Bilateral Cysts Causing Acute Polyhydramnios

In recent years, fetal ovarian cysts have been diagnosed more frequently because of improved prenatal sonographic techniques. These cysts vary in size, can be simple or complex, and are commonly unilateral. Intrauterine complications such as torsion and rupture may occur, and treatment options vary from conservative management to antenatal aspiration, early delivery, and neonatal surgery. We report the case of a unilateral, complex fetal ovarian cyst that progressed rapidly to bilateral complex cysts and was accompanied by acute onset of severe polyhydramnios. Such symptoms represent a considerable potential risk for bilateral ovarian loss. We are unaware of any previously published reports of such progression.

Nucleated red blood cells in uncomplicated prolonged pregnancy

OBJECTIVE: Elevated counts of nucleated red blood cells (NRBCs), as well as prolongation of pregnancy, have been suggested as predictors of adverse perinatal outcome. However, the association between these 2 variables has received only minimal attention. We sought to evaluate fetal NRBCs in prolonged pregnancies. METHODS: Umbilical cord blood was prospectively collected at delivery from 75 prolonged (at or beyond 287 days) pregnancies. One hundred and fifty term deliveries (260–286 days) served as controls. All pregnancies were accurately dated with the use of first-trimester sonography. Fetal biophysical profile testing was initiated at 40 weeks of gestation. Patients were delivered if they were in spontaneous labor or the biophysical profile was nonreassuring or by 42 weeks of gestation. Nucleated red blood cell counts were expressed per 100 white blood cells (WBC). Umbilical artery pH studies, as well as other demographic and clinical variables, were obtained. RESULTS: Prolonged pregnancy was associated with a significantly increased incidence of induction of labor and a greater birth weight. There were no other differences between the study group and controls. The median NRBCs per 100 WBCs in prolonged pregnancy was not significantly elevated over the term values (median 3, range 0–35 versus median 3, range 0–34, respectively; P = .25). Neonatal outcome was also comparable between groups. The univariate regression analysis demonstrated a significant association between elevated NRBC counts and low arterial cord blood pH (P < .008, R = 0.175), elevated base excess (P = .02, R = 0.149), low platelet counts (P = .046, R = 0.134), and male gender (P = .028). Stepwise regression analysis revealed that low arterial cord blood pH and male gender were the only independent variables predicting elevated NRBC counts at birth. CONCLUSION: The findings of this study suggest that elevated NRBC counts are associated with specific pregnancy complications rather than uncomplicated prolonged pregnancies in general. LEVEL OF EVIDENCE: II-2

Does the availability of maternal HbA1c results improve the accuracy of sonographic diagnosis of macrosomia

To determine whether measuring maternal glycosylated hemoglobin (HbA1c) can improve the accuracy of sonographic estimation of fetal macrosomia.

Inferior vena cava thrombosis presenting as non‐immune hydrops in the fetus of a woman with diabetes

We present a rare case of non‐immune hydrops fetalis (NIHF) caused by a thrombus in the inferior vena cava in a neonate with low levels of anti‐thrombin III. The diagnosis of (NIHF) was made in utero in a 43‐year‐old woman with poorly controlled gestational diabetes who subsequently developed pre‐eclampsia. Cesarean section was performed due to fetal compromise and worsening pre‐eclampsia. The thrombus resolved after neonatal treatment with heparin. Copyright

Values of amniotic fluid index in cases of preterm premature rupture of membranes

Abstract Aims: To measure the amniotic fluid index (AFI) in cases of preterm premature rupture of membranes (PPROM). Methods: A retrospective study of pregnancies complicated with PPROM was performed. Data collected included maternal age, parity, gestational age at PPROM and at birth, and AFI on admission. Gestational age matched AFIs were obtained from a low-risk control group in a 3:1 ratio. Results: One hundred and two singleton pregnancies with PPROM formed the study population. The mean gestational age at PPROM was 29±5.3 weeks (range: 14–36.6 weeks). The mean AFI in the PPROM and the control groups was 5.8±3.6 cm (0–18.5 cm) and 13.7±3.2 cm (7.3–24.4 cm), respectively (P<0.001). The area under the ROC curve of AFI in the prediction of PPROM was 0.95 (P<0.001). An AFI of ≤10 cm had sensitivity, specificity, positive and negative predictive values of 89.2%, 88.5%, 72.2% and 96%, respectively, in supporting the diagnosis of PPROM. Conclusions: The presence of low AFI supports the diagnosis of PPROM. ROC curve analysis revealed that an AFI ≤10 cm is the optimal cut-off value in the suspicion of PPROM.

Fetal pyelectasis: does fetal gender modify the risk of major trisomies?

OBJECTIVE: Several studies have noted an increased prevalence of pyelectasis in male fetuses. It is speculated that pyelectasis represents a normal physiologic variant in males, whereas its presence in females indicates an increased risk of chromosomal abnormalities. Thus, we sought to investigate the association between fetal gender and the risk of major trisomies in fetuses with pyelectasis. METHODS: Retrospective analysis of a Genzyme Genetics amniocentesis database (1995 to 2004) was performed. Specimens obtained after an ultrasonographic finding of pyelectasis were eligible for analysis. The prevalence of major trisomies (trisomy 13, 18, or 21) in male and female fetuses with pyelectasis was compared using binomial distribution. RESULTS: A total of 760,495 amniocentesis specimens were analyzed. Fetal pyelectasis was reported in 671 cases. A male predominance, with a male-to-female ratio of 2.14:1 (457 compared with 214) was statistically significant (P < .001). A major trisomy was detected in 26 male fetuses (5.7%): 18 cases of trisomy 21, 2 cases of trisomy 18, and 6 cases of trisomy 13. Nine female fetuses had a major trisomy (4.2%): 6 cases of trisomy 21 and 3 cases of trisomy 13. There was no significant difference in the overall prevalence of trisomies between male and female fetuses (P = .14). CONCLUSION: We concur with previous studies documenting a higher prevalence of pyelectasis in male fetuses. In addition, our results indicate that the prevalence of major trisomies among fetuses with pyelectasis is unlikely to be dependent on fetal gender. Thus, counseling patients with regard to the genetic implications of fetal pyelectasis should be gender independent. LEVEL OF EVIDENCE: II-2