A compelling symmetry: The extended fetuses-at-risk perspective on modal, optimal and relative birthweight and gestational age

Background The relationship between several intriguing perinatal phenomena, namely, modal, optimal, and relative birthweight and gestational age, remains poorly understood, especially the mechanism by which relative birthweight and gestational age resolve the paradox of intersecting perinatal mortality curves. Methods Birthweight and gestational age distributions and birthweight- and gestational age-specific perinatal death rates of low- and high-risk cohorts in the United States, 2004–2015, were estimated using births-based and extended fetuses-at-risk formulations. The relationships between these births-based distributions and rates, and the first derivatives of fetuses-at-risk birth and perinatal death rates were examined in order to assess how the rate of change in fetuses-at-risk rates affects gestational age distributions and births-based perinatal death rate patterns. Results Modal gestational age typically exceeded optimal gestational age because both were influenced by the peak in the first derivative of the birth rate, while optimal gestational age was additionally influenced by the point at which the first derivative of the fetuses-at-risk perinatal death rate showed a sharp increase in late gestation. The clustering and correlation between modal and optimal gestational age within cohorts, the higher perinatal death rate at optimal gestational age among higher-risk cohorts, and the symmetric left-shift in births-based gestational age-specific perinatal death rates in higher-risk cohorts explained how relative gestational age resolved the paradox of intersecting perinatal mortality curves. Conclusions Changes in the first derivative of the fetuses-at-risk birth and perinatal death rates underlie several births-based perinatal phenomena and this explanation further unifies the fetuses-at-risk and births-based models of perinatal death.

A compelling symmetry: The extended fetuses-at-risk perspective on modal, optimal and relative birthweight and gestational age

BackgroundThe relationship between several intriguing perinatal phenomena, namely, modal, optimal, and relative birthweight and gestational age, remains poorly understood, especially the mechanism by which relative birthweight and gestational age resolve the paradox of intersecting perinatal mortality curves.MethodsBirthweight and gestational age distributions and birthweight- and gestational age-specific perinatal death rates of low- and high-risk cohorts in the United States, 2004-2015, were estimated using births-based and extended fetuses-at-risk formulations. The relationships between these births-based distributions and rates, and the first derivatives of fetuses-at-risk birth and perinatal death rates were examined in order to assess how the rate of change in fetuses-at-risk rates affects gestational age distributions and births-based perinatal death rate patterns.ResultsModal gestational age typically exceeded optimal gestational age because both were influenced by the peak in the first derivative of the birth rate, while optimal gestational age was additionally influenced by the point at which the first derivative of the fetuses-at-risk perinatal death rate showed a sharp increase in late gestation. The clustering and correlation between modal and optimal gestational age within cohorts, the higher perinatal death rate at optimal gestational age among higher-risk cohorts, and the symmetric left-shift in births-based gestational age-specific perinatal death rates in higher-risk cohorts explained how relative gestational age resolved the paradox of intersecting perinatal mortality curves.ConclusionsChanges in the first derivative the fetuses-at-risk birth and perinatal death rates underlie several births-based perinatal phenomena and this explanation further unifies the fetuses-at-risk and births-based models of perinatal death.

Pregnancy and delivery in advanced maternal age: epidemiologic aspects and prognosis

Introduction: Pregnancies in old age are a topical subject for both women and health professionals because of their increasing frequency. In Chad, pregnancy and childbirth in old age is a frequent phenomenon. So, we initiated this study to evaluate the prognosis of pregnancy and childbirth in old age. Patients and method: This was a descriptive prospective study about maternal and fetal prognosis of pregnancies in old age covering a period of 3 months, from 1st January to 31st March 2017. Were included in the study all parturient aged ≥ 35 years, a pregnancy age ≥ 28 years that have accepted to participate to this study. Results: During the study period we recorded 104 parturient with age ≥ 35 years among 8442 parturient giving a frequency of 1.23%. The average age was 36.7 years with extremes age of 35 and 45 years. Thirty five year-old were more represented with 45.2%. The majority of patients were married. The no uneducated had represented 75% of cases. The multiparous were more represented with 65.4%. Sixty-five (62.5%) did attended prenatal consultation. The pregnancy was at term for ninety-three (89.4%). The majority delivered by the vaginal route (87.5%). Hypertension was the most common complication with 12.8%. No maternal death has been reported. Fifty-eight newborns (53.7% had a birth weight between 3500-3999g. Thirty two newborns (29.6%). presented complications Perinatal asphyxia was the most common fetal complication with 8.3%. However, the perinatal death rate was 17.6%. Conclusion: Childbirth among women age ≥ 35 years is an infrequent phenomenon, with complications recorded that can be maternal or fetal.

An Analysis of the NSW Midwives Data Collection over an 11-Year Period to Determine the Risks to the Mother and the Neonate of Induced Delivery for Non-Obstetric Indication at Term

Objective. To determine the risks of induced term delivery to the mother and neonate at different gestational ages in the absence of obstetric indications. Study Design. All deliveries in New South Wales (NSW) between 1998 and 2008 were reviewed from the MDC. Uncomplicated pregnancies which were induced for non-obstetric reasons after 37 completed weeks were reviewed. This was a retrospective, historical cohort study, and both maternal and neonatal outcomes were analysed and compared between different gestational age groups. Results. An analysis of the data shows that induction of labour after 37 completed weeks exposes the fetus and mother to different levels of risk at different gestations. Conclusion. In an uncomplicated pregnancy, induction of labour is associated with the highest rate of neonatal complication at 37 weeks as compared with rates at later gestations. With each ensuing week, the neonatal outcome improves. At 40 weeks the likelihood of neonatal intensive care admission, low Apgar scores, and perinatal death rate is at its lowest, and then there is a slight but not significant rise after 41 weeks. The likelihood of caesarean section is the lowest when inductions are carried out at 39 weeks and is the highest at 41 weeks and over.

Epidemiology of congenital malformations of the central nervous system in (a) Aberdeen and (b) Scotland

SummaryThe incidence of anencephalus and other malformations of the central nervous system (CNS) is much higher in the United Kingdom than in other countries of Western Europe which were not industrialized to the same extent. In the UK the incidence is highest in the unskilled manual occupational group, especially in the large cities of the North of England, Scotland and Northern Ireland. Standards of living have been low in these areas for many years and deteriorated sharply at the time of the worldwide industrial depression from 1928 to 1934. The population tended to be stunted in stature and to show other signs of chronic malnutrition.The cohort of women born in these years had an unusually high stillbirth rate from anencephalus (and from all other CNS malformations) from about 1946 onwards. It was highest in the early 1960s when these women were at the peak of their reproductive activity. This suggests that the severe malnutrition to which they were subjected before and soon after birth resulted in severe damage, which reduced their reproductive efficiency as demonstrated by the unusually high perinatal death rate from all CNS malformations. Not surprisingly the death rate rose sooner, lasted longer and reached a higher level in social classes IV and V than in social classes I and II. Other evidence of damage was an increase in the incidence of low birth weight babies with a corresponding increase in the perinatal death rate from this cause.In Scotland the stillbirth rate from anencephalus was approximately 2·1 per 1000 in 1948–49, 3·4 at its highest point between 1961 and 1963 and 2·1 in 1968, by which time the women born in the years of the depression had completed their childbearing. A teratogen acting during a particular period of time could not provide a satisfactory explanation for this sequence of events.

Perinatal vs. Neonatal Mortality

The annual summary of vital statistics for 1971 was noted in the December 1972 issue. I am confused as to the method of reporting newborn deaths. The recently revised Standards and Recommendations, Hospital Care of Newborn Infants handbook recommends reporting a perinatal death rate for international comparability. Stillbirths after 28 weeks and neonatal deaths under seven days* are used as a more relative means of assessing conditions surrounding birth. The following formula is used to calculate the perinatal death rate:

Letters to the Editor

Dr. Houck is quite correct that the perinatal death rate is very useful as a method of studying newborn mortality; many deaths just before birth have the same causes as those which occur immediately after a live birth. The major problem in using such a rate for international comparison relates to reliability of reporting and definition of the period of gestation. It is easy to give a precise and uniform definition of a live birth and the age period after birth may also be determined with exactitude.