Lower perinatal mortality in preterm born twins than in singletons: a nationwide study from The Netherlands.

BACKGROUND: Twin pregnancies are at increased risk for perinatal morbidity and death because of many factors that include a high incidence of preterm delivery. Compared with singleton pregnancies, overall perinatal risk of death is higher in twin pregnancies; however, for the preterm period, the perinatal mortality rate has been reported to be lower in twins. OBJECTIVE: The purpose of this study was to compare perinatal mortality rates in relation to gestational age at birth between singleton and twin pregnancies, taking into account socioeconomic status, fetal sex, and parity. STUDY DESIGN: We studied perinatal mortality rates according to gestational age at birth in 1,502,120 singletons pregnancies and 51,658 twin pregnancies without congenital malformations who were delivered between 2002 and 2010 after 28 weeks of gestation. Data were collected from the nationwide Netherlands Perinatal Registry. RESULTS: Overall the perinatal mortality rate in twin pregnancies (6.6/1000 infants) was higher than in singleton pregnancies (4.1/1000 infants). However, in the preterm period, the perinatal mortality rate in twin pregnancies was substantially lower than in singleton pregnancies (10.4 per 1000 infants as compared with 34.5 per 1000 infants, respectively) for infants who were born at <37 weeks of gestation; this held especially for antepartum deaths. After 39 weeks of gestation, the perinatal mortality rate was higher in twin pregnancies. Differences in parity, fetal sex, and socioeconomic status did not explain the observed differences in outcome. CONCLUSION: Overall the perinatal mortality rate was higher in twin pregnancies than in singleton pregnancies, which is most likely caused by the high preterm birth rate in twins and not by a higher mortality rate for gestation, apart from term pregnancies. During the preterm period, the antepartum mortality rate was much lower in twin pregnancies than in singleton pregnancies. We suggest that this might be partially due to a closer monitoring of twin pregnancies, which indirectly suggests a need for closer surveillance of singleton pregnancies.

Perinatal mortality in preterm births: an analysis of causes, presence of substandard care and avoiding mortality in three Dutch regions.

OBJECTIVE: To analyze the causes and underlying events in cases of perinatal mortality (PNM) in preterm children. SETTING: Three regions within the Netherlands. STUDY DESIGN: For this study, we combined data of a PNM audit over a 1-year (2003-2004) with the corresponding data of its source population (n=22,189). In the perinatal audit, all cases of perinatal death have been assessed by multi disciplinary teams of professionals in perinatal care in a consensus model for cause of death and the presence of substandard care factors (SSF). In this article, we restricted our analysis to children born between 22+0 and 37+0 weeks of pregnancy (≥154 and <259 days). We also evaluated avoidability of preterm birth and avoidability of preterm perinatal mortality (PPM) in cases with and without SSF. RESULTS: Of 1885 preterm children, 166 died perinatally (8.81%). The two most important determinants were small-for-gestational-age;ib47.6% of all cases with gestational age (GA) ≥25 weeks;ic and previous PNM (21.1%). In addition, PPM was substantially increased in mothers of non-Dutch origin (PPM 12.1% vs. 6.6% in children of Dutch mothers relative risk (RR)=1.88, 95% confidence interval=1.46-2.43) and in mothers in the age group 20-26 years (PPM 13.4% vs. <9% in all other categories, RR=1.69, 95% confidence interval=1.21-2.38). In 22.6% of the cases perinatal death was considered to be avoidable while in 17.0% perinatal death was related to SSF by caregivers. CONCLUSIONS: Immediate and appropriate actions by both caregivers and care receivers in case of early signals of possible preterm labor may reduce PNM in this category in the Netherlands by more than 20%. Improvement in surveillance of fetal growth may reduce mortality significantly in the preterm gestational period.

Avoidable mortality in small-for-gestational-age children in the Netherlands.

OBJECTIVE: To analyze avoidable perinatal mortality in small-for-gestational-age (SGA) children. METHODS: All SGA-children (< or =10(th) percentile) among 22,189 newborns delivered after 24 weeks' gestation (175 days), from three regions of the Netherlands during 2003-2004 were evaluated. Cases of perinatal mortality were identified and assessed in a consensus model by perinatal audit groups for cause of death and the presence of substandard care factors (SSF). We analyzed all singleton SGA-cases with and without SSF for avoidable perinatal mortality. RESULTS: Out of 20,927 singletons, 2396 newborns were SGA. Of those, 59 died perinatally (2.46%), and 55 of which were assessed by perinatal audit groups. SSF by caregivers were found in 22 cases (40%). In 16 of these cases (29%) the relation to the perinatal death was considered possible or (very) probable. Of the cases without SSF by caregivers, 15 cases (25%) could possibly have been avoided: in 13 cases an avoidable condition and in 2 cases avoidable death were identified. Failure in the correct and timely diagnosis of fetal growth restriction appears to be an important issue in all cases of perinatal mortality in SGA-children. Before referral growth restriction was suspected only in 22% of all SGA cases during the third trimester of pregnancy. CONCLUSIONS: More adequate action by caregivers could decrease perinatal mortality in nearly 1/3 among SGA-children. Adjustments in pregnancy monitoring, especially in low-risk pregnancies, such as routine ultrasound biometry examination, may improve the accuracy in detecting growth deviations and decreasing the number of possibly avoidable cases of perinatal mortality in this category.

Value of a single early third trimester fetal biometry for the prediction of birth weight deviations in a low risk population.

OBJECTIVE: To analyze the value of a single ultrasound biometry examination at the onset of the third trimester of pregnancy for the detection of small-for-gestational-age (SGA) and large-for-gestational-age (LGA) at birth in a low risk population. The aim of this study was to develop a simple and useful method for the detection of growth deviations during pregnancy in primary care (midwife or general practitioner) practices. SETTING: A Dutch primary care midwifery practice. STUDY DESIGN: In an earlier study, we developed parity and sex specific fetal growth charts of abdominal circumference (AC) and head circumference (HC) on the basis of ultrasound data of a low-risk midwifery population in the Netherlands. In the present study, we calculated sensitivity, specificity and predictive values at different cut-off points of AC and HC for the prediction of growth deviations at birth. Patients booked for perinatal care between 1 January 1993 and 31 December 2003 (n=3449) were used for the identification of cut-off points (derivation cohort) and those admitted between 1 January 2004 and 31 December 2005 (n=725) were used to evaluate the performance of these cut-offs in an independent population (validation cohort). For the determination of SGA and macrosomia at birth, we used the recently published Dutch birth weight percentiles. RESULTS: Most promising cut-offs were AC or=75(th) percentile for the prediction of macrosomia (birth weight >or=90(th) percentile). Within the validation cohort these cut-offs performed slightly better than in the derivation cohort. For the prediction of SGA, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 53% (95% CI 49-58%), 81% (95% CI 80-83%), 26% (95% CI 23-29%), and 93% (95% CI 93-94%), respectively. The false positive rate was 74%. For the prediction of macrosomia, the values of these parameters were 64% (95% CI 59-69%), 80% (95% CI 78-81%), 23% (95% CI 20-26%), and 96% (95% CI 95-97%), respectively. Here, false positive rate was 77%. No cut-offs were found that predicted extreme birth weight deviations (or=97.7 percentile) sufficiently well. CONCLUSIONS: In a low risk population, we could predict future growth deviations with a higher sensitivity and in a significant earlier stage (at the onset of the third trimester of pregnancy) than with the use of conventional screening methods (i.e., palpation of the uterus only and fundus-symphysis measurement). Sonographic measurement of fetal abdominal circumference enables to detect more than half of cases of SGA at birth and more than two-thirds of cases of macrosomia with acceptable false-positive rates. We suggest that fetuses with biometry results below the 25(th) percentile or above the 75(th) percentile at the onset of the third trimester of pregnancy should be more intensively investigated in order to distinguish between pathology (e.g., IUGR or macrosomia) and physiology and to decide about the appropriate level of further perinatal care.