Obstetric infections and clinical characteristics of maternal sepsis: a hospital-based retrospective cohort study.

Sepsis is responsible for 50% of intrahospital maternal deaths worldwide. Incidence is increasing in both low and middle-, and high-income countries. There is little data on incidence and clinical outcomes of obstetric infections including maternal sepsis in the Nordic countries. The aims of this study are to give estimates of the occurrence of obstetric infections and maternal sepsis in a Norwegian hospital cohort, assess the quality of management of maternal sepsis cases, and evaluate the usefulness of diagnostic codes to identify maternal sepsis retrospectively. We conducted a retrospective cohort study of pregnant, labouring, post-abortion, and postpartum women. We assessed the accuracy of the diagnostic code most frequently applied for maternal sepsis, O85. We found 7.8% (95% confidence interval 7.1-8.5) infection amongst pregnant, labouring, and postpartum women. The incidence of maternal sepsis was 0.3% (95% confidence interval 0.2-0.5), and the majority of sepsis cases were recorded in the postpartum period. Two thirds of women were given broad-spectrum antibiotics at the time sepsis was diagnosed, but only 15.4% of women with puerperal sepsis were given antimicrobials in accordance with national guidelines. When used retrospectively, obstetric infection codes are insufficient in identifying both maternal and puerperal sepsis, with only 20.3% positive predictive value for both conditions. In conclusion, obstetric infections contribute significantly to maternal morbidity in Norway's second largest maternity hospital. This study provides incidences of maternal infections for hospitalised patients in temporal relation to pregnancy, labour, abortion and the postpartum period, knowledge which is valuable for planning of health care services and allocation of resources. In addition, the study highlights areas where improvement is needed in clinical handling of maternal sepsis. There is need for studies on the management quality and use of correct diagnostic codes in this patient category.

Shoulder dystocia by severity in families: A nationwide population study.

INTRODUCTION: Previous studies have established a history of shoulder dystocia as an important risk factor for shoulder dystocia, but studies on shoulder dystocia by severity are scarce. It is unknown if shoulder dystocia tends to be passed on between generations. We aimed to assess the recurrence risk of shoulder dystocia by severity in the same woman and between generations on both the maternal and paternal side. We also assessed the likelihood of a second delivery and planned cesarean section after shoulder dystocia. MATERIAL AND METHODS: This was a population-based cohort study, using data from the Medical Birth Registry of Norway. To study recurrence in the same mother, we identified 1 091 067 pairs of first and second, second and third, and third and fourth births in the same mother. To study intergenerational recurrence, we identified an individual both as a newborn and as a mother or father in 824 323 mother-offspring pairs and 614 663 father-offspring pairs. We used Bayesian log-binomial multilevel regression to calculate relative risks (RR) with 95% credible intervals. RESULTS: In subsequent deliveries in the same woman the unadjusted RR of recurrence was 7.05 (95% credible interval 6.39-7.79) and 2.99 (2.71-3.31) after adjusting for possible confounders, including current birthweight. The RRs were higher with severe shoulder dystocia as exposure or outcome. With severe shoulder dystocia as both exposure and outcome, unadjusted and adjusted RR was 20.42 (14.25-29.26) and 6.29 (4.41-8.99), respectively. Women with severe and mild shoulder dystocia and those without had subsequent delivery rates of 71.1, 68.9 and 69.0%, respectively. However, the rates of planned cesarean section in subsequent deliveries for those without shoulder dystocia, mild and severe were 1.3, 5.2 and 16.0%, respectively. On the maternal side the unadjusted inter-generational RR of recurrence was 2.82 (2.25-3.54) and 1.41 (1.05-1.90) on the paternal side. Corresponding adjusted RRs were 1.90 (1.51-2.40) and 1.19 (0.88-1.61), respectively. CONCLUSIONS: We found a strong recurrence risk of shoulder dystocia, especially severe, in subsequent deliveries in the same woman. The inter-generational recurrence risk was higher on the maternal than paternal side. Women with a history of shoulder dystocia had more often planned cesarean section.

Paternal and maternal birthweight and offspring risk of macrosomia at term gestations: A nationwide population study.

BACKGROUND: There is a paucity of data on whether parents' macrosomia (birthweight ≥4500 g) status influences the risk of macrosomia in the offspring. The role of maternal overweight in the generational effect of macrosomia is not known. OBJECTIVE: To estimate the risk of macrosomia by parental birthweight at term and evaluate if this risk varied with maternal body mass index (BMI, kg/m2) early in pregnancy. METHODS: We used data from the Medical Birth Registry of Norway on all singleton term births (37-42 gestational weeks) during 1967-2017. The primary exposure was parental macrosomia, and the outcome was macrosomia in the second generation. The secondary exposure was maternal BMI. We used binomial regression to calculate relative risk (RR) with a 95% confidence interval. We assessed potential unmeasured confounding and selection bias using a probabilistic bias analysis and performed analyses with and without imputation for variables with missing values. RESULTS: The data included 647,957 singleton parent-offspring trios born at term. The prevalence of macrosomia was 3.2% (n = 41,396) in the parental generation and 4.0% (n = 25,673) in the offspring generation. Macrosomia in parents was associated with an increased risk of macrosomia in offspring, with the RR for both parents were born macrosomic being 6.53 (95% confidence interval [CI] 5.31, 8.05), only mother macrosomic 3.37 (95% CI 3.17, 3.57) and only father macrosomic RR 2.22 (95% CI 2.12, 2.33). These risks increased by maternal BMI in early pregnancy: if both parents were born macrosomic, 17% of infants were macrosomic among mothers with normal BMI. If both parents were macrosomic and the mothers were obese, 31% of offspring were macrosomic. Macrosomia-related adverse outcomes did not differ with parental macrosomia status. CONCLUSIONS: Parents' weight at birth and maternal BMI appear to be strongly associated with macrosomia in the offspring delivered at term gestations.

Risk factors and recurrence of cause-specific postpartum hemorrhage: A population-based study.

OBJECTIVE: To explore risk profiles of the different types of postpartum hemorrhage (PPH >500ml or severe PPH >1500ml) and their recurrence risks in a subsequent delivery. METHODS: With data from The Medical Birth Registry of Norway and Statistics Norway we performed a population-based cohort study including all singleton deliveries in Norway from 1967-2017. Multilevel logistic regression was used to calculate odds ratio (OR), with 95% confidence interval (CI), with different PPH types (PPH >500ml or PPH >1500ml (severe PPH) combined with retained placenta, uterine atony, obstetric trauma, dystocia, or undefined cause) as outcomes. RESULT: We identified 277 746 PPH cases of a total of 3 003 025 births (9.3%) from 1967 to 2017. Retained placenta (and/or membranes) was most often registered as severe PPH (29.3%). Maternal, fetal, and obstetric characteristics showed different associations with the PPH types. Male sex of the neonate was associated with reduced risk of PPH. This effect was strongest on PPH due to retained placenta (adjusted OR, (aOR): 0.80, 95% CI 0.78-0.82), atony (aOR 0.92, 95% CI: 0.90-0.93) and PPH with undefined cause (aOR 0.96, 95% CI: 0.95-0.97). Previous cesarean section showed a strong association with PPH due to dystocia (aOR of 13.2, 95% CI: 12.5-13.9). Recurrence risks were highest for the same type: PPH associated with dystocia (aOR: 6.8, 95% CI: 6.3-7.4), retained placenta and/or membranes (aOR: 5.9, 95% CI: 5.5-6.4), atony (aOR: 4.0, 95% CI: 3.8-4.2), obstetric trauma (aOR: 3.9, 95% CI: 3.5-4.3) and PPH of undefined cause (aOR: 2.2, 95% CI: 2.1-2.3). CONCLUSION: Maternal, fetal and obstetric characteristics had differential effects on types of PPH. Recurrence differed considerably between PPH types. Retained placenta was most frequently registered with severe PPH, and showed strongest effect of sex; delivery of a boy was associated with lower risk of PPH. Previous cesarean increased the risk of PPH due to dystocia.

Recurrence of postpartum hemorrhage, maternal and paternal contribution, and the effect of offspring birthweight and sex: a population-based cohort study.

PURPOSE: This study examines individual aggregation of postpartum hemorrhage (PPH), paternal contribution and how offspring birthweight and sex influence recurrence of PPH. Further, we wanted to estimate the proportion of PPH cases attributable to a history of PPH or current birthweight. METHODS: We studied all singleton births in Norway from 1967 to 2017 using data from Norwegian medical and administrational registries. Subsequent births in the parents were linked. Multilevel logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CI) for PPH defined as blood loss > 500 ml, blood loss > 1500 ml, or the need for blood transfusion in parous women. Main exposures were previous PPH, high birthweight, and fetal sex. We calculated adjusted population attributable fractions for previous PPH and current high birthweight. RESULTS: Mothers with a history of PPH had three- and sixfold higher risks of PPH in their second and third deliveries, respectively (adjusted OR 2.9; 95% CI 2.9-3.0 and 6.0; 5.5-6.6). Severe PPH (> 1500 ml) had the highest risk of recurrence. The paternal contribution to recurrence of PPH in deliveries with two different mothers was weak, but significant. If the neonate was male, the risk of PPH was reduced. A history of PPH or birthweight ≥ 4000 g each accounted for 15% of the total number of PPH cases. CONCLUSION: A history of PPH and current birthweight exerted strong effects at both the individual and population levels. Recurrence risk was highest for severe PPH. Occurrence and recurrence were lower in male fetuses, and the paternal influence was weak.

Recurrence of postpartum hemorrhage in relatives: A population-based cohort study.

INTRODUCTION: Studies on the family aggregation of postpartum hemorrhage (PPH) are scarce and with inconsistent results, and to what extent current birthweight influences recurrence between relatives remains to be studied. Further, family aggregation of PPH has been studied from an individual, but not from a public heath perspective. We aimed to investigate family aggregation of PPH in Norway, how birthweight influences these effects, and to estimate the proportion of PPH cases attributable to a family history of PPH and current birthweight. MATERIAL AND METHODS: Using data from the Medical Birth Registry of Norway, Statistics Norway, and Central Population Registry of Norway we identified individuals as newborns, parents, grandparents, and full and half-siblings, and studied 1 002 687 mother-offspring, 841 164 father-offspring, and 761 011 both-parents-offspring pairs. We used multilevel logistic regression to calculate odds ratios (OR) with 95% CI. RESULTS: If the birth of the mother but not of the father involved PPH, then the OR of PPH (>500 mL) in the next generation was 1.44 (95% CI 1.39-1.49). If the birth of the father but not of the mother involved PPH, then OR was 1.12 (95% CI 1.08-1.16). These effects were stronger in severe PPH. Recurrence between siblings was highest between full sisters (OR 1.47, 95% CI 1.41-1.52), followed by maternal half-sisters, paternal half-sisters, and partners of full brothers. A family history of PPH or birthweight of 4000 g or more accounted for ≤5% and 15% of the total number of PPH cases, respectively. CONCLUSIONS: A history of PPH in relatives influenced the recurrence risk of PPH in a dose-response pattern consistent with the anticipated proportion of shared genes. The recurrence was highest through the maternal line.

Pre-gestational diabetes: Maternal body mass index and gestational weight gain are associated with augmented umbilical venous flow, fetal liver perfusion, and thus birthweight.

OBJECTIVES: To assess how maternal body mass index and gestational weight gain are related to on fetal venous liver flow and birthweight in pregnancies with pre-gestational diabetes mellitus. METHODS: In a longitudinal observational study, 49 women with pre-gestational diabetes mellitus were included for monthly assessments (gestational weeks 24-36). According to the Institute Of Medicine criteria, body mass index was categorized to underweight, normal, overweight, and obese, while gestational weight gain was classified as insufficient, appropriate or excessive. Fetal size, portal flow, umbilical venous flow and distribution to the fetal liver or ductus venosus were determined using ultrasound techniques. The impact of fetal venous liver perfusion on birthweight and how body mass index and gestational weight gain modified this effect, was compared with a reference population (n = 160). RESULTS: The positive association between umbilical flow to liver and birthweight was more pronounced in pregnancies with pre-gestational diabetes mellitus than in the reference population. Overweight and excessive gestational weight gain were associated with higher birthweights in women with pre-gestational diabetes mellitus, but not in the reference population. Fetuses of overweight women with pre-gestational diabetes mellitus had higher umbilical (p = 0.02) and total venous liver flows (p = 0.02), and a lower portal flow fraction (p = 0.04) than in the reference population. In pre-gestational diabetes mellitus pregnancies with excessive gestational weight gain, the umbilical flow to liver was higher than in those with appropriate weight gain (p = 0.02). CONCLUSIONS: The results support the hypothesis that umbilical flow to the fetal liver is a key determinant for fetal growth and birthweight modifiable by maternal factors. Maternal pre-gestational diabetes mellitus seems to augment this influence as shown with body mass index and gestational weight gain.

Risk factors for surgical site infection following cesarean delivery: A hospital-based case-control study.

INTRODUCTION: Cesarean section is the single most important risk factor for postpartum infection. Where the rest of the world shows increasing trends, the cesarean section rates are low in Norway and risk factors for infection after cesarean section may differ in high and low cesarean section settings. The goal of this study was to examine independent risk factors for surgical site infection after cesarean delivery in a setting of low cesarean section rates. MATERIAL AND METHODS: We conducted a hospital-based case-control study at Haukeland University Hospital. We included women who presented to our hospital with surgical site infection after cesarean section during the years 2014-2016 (n = 75). Controls were selected at a ratio of 2:1 (n = 148). Cases and controls were compared with respect to maternal and pregnancy characteristics using uni- and multivariable logistic regression models. Main outcome measures were anticipated risk factors for surgical site infection. RESULTS: The occurrence of surgical site infection was 0.4% and 5.4% after elective and emergency cesarean section, respectively. Compared to women without surgical site infection, women with surgical site infection were almost thrice more obese before pregnancy (OR 2.8, 95% CI 1.2-7.0), four times more likely to have preexisting psychiatric conditions (OR 4.4, 95% CI 1.1-17.6), and five times more likely to receive blood transfusion (OR 5.1, 95% CI 1.4-18.8). Signs of infection during labor was a marginally significant risk factor for surgical site infection (OR 2.0, 95% CI 1.0-5.4). CONCLUSIONS: Emergency cesarean section was a significant risk factor for surgical site infection. Pregestational obesity, preexisting psychiatric conditions, and blood transfusion during or following delivery, were independent risk factors for surgical site infection. Signs of infection during labor was a marginally significant risk factor. Women with either of these risk factors should be carefully monitored and evaluated for signs of infection in the postpartum period.

Social inequalities in the provision of obstetric services in Norway 1967-2009: a population-based cohort study.

BACKGROUND: Socioeconomic (SE) inequalities have been observed in a number of adverse outcomes of pregnancy and many of the risk factors for such outcomes are associated with a low SE level. However, SE inequalities persist even after adjustment for these risk factors. Less well-off women are more vulnerable, but may also get less adequate health services. The objective of the present study was to assess possible associations between SE conditions in terms of maternal education as well as ethnic background and obstetric care. METHODS: A population-based national cohort study from the Medical Birth Registry of Norway. The study population comprised 2 305 780 births from the observation period 1967-2009. Multilevel analysis was used because of the hierarchical structure of the data. Outcome variables included induction of labour, epidural analgesia, caesarean section, neonatal intensive care and perinatal death. RESULTS: While medical interventions in the 1970s were employed less frequently in women of short education and non-western immigrants, this difference was eliminated or even reversed towards the end of the observation period. However, an excess perinatal mortality in both the short-educated [adjusted relative risk (aRR) = 2.49] and the non-western immigrant groups (aRR = 1.75) remained and may indicate increasing health problems in these groups. CONCLUSION: Even though our study suggests a fair and favourable development during the last decades in the distribution across SE groups of obstetric health services, the results suggest that the needs for obstetric care have increased in vulnerable groups, requiring a closer follow-up.

Low risk pregnancies after a cesarean section: Determinants of trial of labor and its failure.

INTRODUCTION: In pregnancies after a previous cesarean section (CS), a planned repeat CS delivery has been associated with excess risk of adverse outcome. However, also the alternative, a trial of labor after CS (TOLAC), has been associated with excess risks. A TOLAC failure, involving a non-planned CS, carries the highest risk of adverse outcome and a vaginal delivery the lowest. Thus, the decision regarding delivery mode is pivotal in clinical handling of these pregnancies. However, even with a high TOLAC rate, as seen in Norway, repeat CSs are regularly performed for no apparent medical reason. The objective of the present study was to assess to which extent demographic, socioeconomic, and health system factors are determinants of TOLAC and TOLAC failure in low risk pregnancies, and whether any effects observed changed with time. MATERIALS AND METHODS: The study group comprised 24 645 second deliveries (1989-2014) after a first delivery CS. Thus, none of the women had prior vaginal deliveries or more than one CS. Included pregnancies were low risk, cephalic, single, and had gestational age ≥ 37 weeks. Data were obtained from the Medical Birth Registry of Norway (MBRN). The exposure variables were (second delivery) maternal age, length of maternal education, maternal country of origin, size of the delivery unit, health region (South-East, West, Mid, North), and maternal county of residence. The outcomes were TOLAC and TOLAC failure, as rates (%), relative risk (RR) and relative risk adjusted (ARR). Changes in determinant effects over time were assessed by comparing rates in two periods, 1989-2002 vs 2003-2014, and including these periods in an interaction model. RESULTS: The TOLAC rate was 74.9%, with a TOLAC failure rate of 16.2%, resulting in a vaginal birth rate of 62.8%. Low TOLAC rates were observed at high maternal age and in women from East Asia or Latin America. High TOLAC failure rates were observed at high maternal age, in women with less than 11 years of education, and in women of non-western origin. The effects of health system factors, i.e. delivery unit size and administrative region were considerable, on both TOLAC and TOLAC failure. The effects of several determinants changed significantly (P < 0.05) from 1989-2002 to 2003-2014: The association between non-TOLAC and maternal age > 39 years became weaker, the association between short education and TOLAC failure became stronger, and the association between TOLAC failure and small size of delivery unit became stronger. CONCLUSION: Low maternal age, high education, and western country of origin were associated with high TOLAC rates, and low TOLAC failure rates. Maternity unit characteristics (size and region) contributed with effects on the same level as individual determinants studied. Temporal changes were observed in determinant effects.

Isolated single umbilical artery and the risk of adverse perinatal outcome and third stage of labor complications: A population-based study.

INTRODUCTION: Isolated single umbilical artery (iSUA) refers to single umbilical artery cords with no other fetal malformations. The association of iSUA to adverse outcome of pregnancy has not been consistently reported, and whether iSUA carries increased risk of third stage of labor complications has not been studied. We aimed to investigate the risk of adverse perinatal outcome, third stage of labor complications, and associated placental and cord characteristics in pregnancies with iSUA. A further aim was to assess the risk of recurrence of iSUA and anomalous cord or placenta characteristics in Norway. MATERIAL AND METHODS: This was a population-based study of all singleton pregnancies with gestational age >16 weeks at birth using data from the Medical Birth Registry of Norway from 1999 to 2014 (n = 918 933). Odds ratios (OR) with 95% confidence intervals were calculated for adverse perinatal outcome (preterm birth, perinatal and intrauterine death, low Apgar score, transferral to neonatal intensive care ward, placental and cord characteristics [placental weight, cord length and knots, anomalous cord insertion, placental abruption and previa]), and third stage of labor complications (postpartum hemorrhage and the need for manual placental removal or curettage) in pregnancies with iSUA, and recurrence of iSUA using generalized estimating equations and logistic regression. RESULTS: Pregnancies with iSUA carried increased risk of adverse perinatal outcome (OR 5.06, 95% confidence interval [CI] 4.26-6.02) and perinatal and intrauterine death (OR 5.62, 95% CI 4.69-6.73), and a 73% and 55% increased risk of preterm birth and small-for-gestational-age neonate, respectively. The presence of iSUA also carried increased risk of a small placenta, placenta previa and abruption, anomalous cord insertion, long cord, cord knot and third stage of labor complications. Women with iSUA, long cord or anomalous cord insertion in one pregnancy carried increased risk of iSUA in the subsequent pregnancy. CONCLUSIONS: The presence of ISUA was associated with a more than five times increased risk of intrauterine and perinatal death and with placental and cord complications. The high associated risk of adverse outcome justifies follow up with assessment of fetal wellbeing in the third trimester, intrapartum surveillance and preparedness for third stage of labor complications.

Altered development of fetal liver perfusion in pregnancies with pregestational diabetes.

BACKGROUND: Pregestational diabetes is associated with fetal macrosomia, and umbilical perfusion of the fetal liver has a role in regulating fetal growth. We therefore hypothesized that pregestational diabetes alters fetal liver blood flow depending on degree of glycemic control. METHODS: In a prospective study, 49 women with pregestational diabetes underwent monthly ultrasound examinations during 24-36 gestational weeks. Blood flow was determined in the umbilical vein, ductus venosus and portal vein, and blood velocity was measured in the left portal vein, the latter reflecting the watershed between splanchnic and umbilical flow. The measurements were compared with reference values by z-score statistics, and the effect of HbA1c assessed. RESULTS: The umbilical venous flow to the liver (z-score 0.36, p = 0.002), total venous liver flow (z-score 0.51, p<0.001) and left portal vein blood velocity (z-score 0.64, p<0.001), were higher in the study group. Normalized portal venous flow was lower (z-score -0.42, p = 0.002), and normalized total venous liver flow tended to be lower after 30 gestational weeks (z-score -0.54, p = 0.047) in the diabetic pregnancies compared with reference values from a low-risk population. The left portal vein blood velocity was positively, and the portal fraction of total venous liver flow negatively correlated with first trimester HbA1C. CONCLUSIONS: In spite of increased umbilical blood distribution to the fetal liver, graded according to glycemic control, the total venous liver flow did not match third trimester fetal growth in pregnancies with pregestational diabetes, thus contributing towards increased perinatal risks and possibly altered liver function with long-term metabolic consequences.

Trial of labor after cesarean section in risk pregnancies: A population-based cohort study.

INTRODUCTION: In most pregnancies after a cesarean section, a trial of labor is an option. The objective of the study was to explore trial of labor and its failure in pregnancies with medical risk conditions, in a population with a high trial of labor rate. MATERIAL AND METHODS: In a cohort study (n = 57 109), using data from the Medical Birth Registry of Norway 1989-2014, women with a second delivery after a first pregnancy cesarean section were included. Preterm, multiple, and non-cephalic deliveries were excluded. The outcomes were trial of labor and failed trial of labor, assessed as rates and relative risk, using deliveries without risk conditions as reference. Temporal trends were assessed by 3-year periods. The exposures were selected medical risk conditions, ie previous offspring death, labor dystocia, diabetes, heart conditions, chronic hypertension, chronic kidney disease, rheumatoid arthritis, thyroid disease, asthma, prepregnancy psychiatric conditions, epilepsy, obesity, gestational diabetes, eclampsia and preeclampsia, gestational hypertension, major malformations, second-pregnancy psychiatric conditions, assisted reproduction, macrosomia, and small-for-gestational-age neonates. Induced onset of labor was compared with spontaneous onset of labor for each condition studied. RESULTS: In risk pregnancies (n = 31 994) the trial of labor rate was 64.9% and failure rate was 27.6%, compared with 74.6% and 16.4% in pregnancies without any of the risk conditions studied (n = 25 115). The lowest trial of labor rates were observed in diabetes type 1 (49.5%), diabetes type 2 (46.7%), maternal heart conditions (54.5%), and pregnancy-related psychiatric conditions (19.7%). The highest failure rates were observed in diabetes type 1 (43.1%), diabetes type 2 (40.3%), maternal obesity (36.9%), gestational diabetes (36.0%), and offspring macrosomia (43.0%). Induced labor was associated with failed trial of labor (P < .05), whereas after spontaneous labor, failure rates were less than 40% in all conditions studied. CONCLUSIONS: In conditions with high rates of failed trial of labor, eg diabetes, macrosomia, and obesity, a planned cesarean section might be a better option than a trial of labor, particularly if induction of delivery might be needed.

Perinatal outcome in births after a previous cesarean section at high trial of labor rates.

INTRODUCTION: Trial of labor (TOLAC) is an option in most preganancies after a cesarean section The objective of the study was to compare perinatal outcome in TOLAC and non-TOLAC deliveries in a population with high TOLAC rates. MATERIAL AND METHODS: This was a cohort study based on population data from the Medical Birth Registry of Norway. We included term, cephalic, single, second deliveries, 1989-2009, after a first cesarean section (n = 43 422). TOLAC, TOLAC failure, non-TOLAC deliveries, and after high-risk and low-risk pregnancies (no risk/any risk), were compared with respect to offspring mortality, 5-minute Apgar score Apgar < 7 and < 4, transfer to a neonatal intensive care unit, and neonatal respiratory distress syndrome. RESULTS: Statistically significant differences were observed (P <0.05). In the low-risk group the offspring mortality was 2.3/1000 in TOLAC compared with 0.9/1000 in non-TOLAC. In the high-risk group, the offspring mortality was 3.7/1000 in TOLAC compared with 0.9/1000 in non-TOLAC, and the 5-minute Apgar score < 4 was 3.1/1000 in TOLAC compared with 0.9/1000 in non-TOLAC. In both risk groups, TOLAC delivery had a higher rate of 5-minute Apgar score < 7. In the low-risk group, non-TOLAC deliveries had a higher rate of neonatal respiratory distress syndrome than TOLAC deliveries. CONCLUSIONS: We observed higher risk of offspring mortality and lower 5-minute Apgar score in TOLAC than in non-TOLAC. Possible causes and preventive measures should be explored.

Estimated date of delivery based on second trimester fetal head circumference: A population-based validation of 21 451 deliveries.

INTRODUCTION: Fetal biometry is used for determining gestational age and estimated date of delivery (EDD). However, the accuracy of the EDD depends on the assumed length of pregnancy included in the calculation. This study aimed at assessing the actual pregnancy length and accuracy of EDD prediction based on fetal head circumference measured at the second trimester. MATERIAL AND METHODS: This was a population-based observational study with the following inclusion criteria: singleton pregnancy, head circumference dating in the second trimester, spontaneous onset or induction of delivery ≥ 294 days of gestation, live birth. The EDD was set anticipating a pregnancy length of 282 days. Bias in the prediction of EDD was defined as the difference between the actual date of birth and the EDD. RESULTS: Head circumference measurements were available for 21 451 pregnancies. Ultrasound-dated pregnancies had a median pregnancy length of 283.03 days, corresponding to a method bias of 1.03 days (95% CI; 0.89-1.16). This bias was dependent on the head circumference at dating, ranging from -1.58 days (95% CI; -3.54 to 1.12) to 3.42 days (95% CI; 1.98-4.31). The median pregnancy length, based on the last menstrual period of women with a regular menstrual cycle (n = 12 985), was 283.15 days (95% CI; 282.91-283.31). A total of 5685 (22.9%, 95% CI; 22.4% to 23.4%) and 886 women (3.6%, 95% CI; 3.3%-3.8%) were still pregnant 7 and 14 days after the EDD, respectively. CONCLUSIONS: Second trimester head circumference measurements can be safely used to predict EDD. A revision of the pregnancy length to 283 days will reduce the bias of EDD prediction to a level comparable with other methods.