Hour of birth and birth assistance: From a primate to a medicalized pattern?

Circadian characteristics of term and preterm labors

The labor is a physiological event considered to have its own circadian (diurnal) rhythm, but some of the data remain conflicting, especially for preterm births. In this retrospective study, we analyzed the circadian trends of labor onset times in the Slovenian birth cohort from 1990 to 2018 with over 550,000 cases of singleton births. The number of term and preterm labor onsets was calculated for each hour in a day and circadian trends were evaluated for each of the study groups by modeling with a generalized Poisson distribution linked with the cosinor regression model using logarithmic link function. The induced labors were taken as the control group since the timing of labor depends mostly on the working schedule of personnel and not on the intrinsic rhythmic characteristics. For induced labors, the main peak in the number of labor cases was observed in the late morning hours (around 10 AM) for all gestational ages. The prominence of this peak becomes smaller in spontaneous premature labors with gradually disrupting rhythmicity in very preterm and extremely preterm cases. Labors starting with spontaneous contractions peak between 6 and 7 AM and lose the rhythmicity at 35 weeks of gestation while labors starting with a spontaneous rupture of membranes peak at 1 AM and lose the rhythmicity at 31 weeks of gestation, suggesting differences in underlying mechanisms. According to our knowledge, this is the first study that shows differences of circadian trends between different types of spontaneous labors, i.e., labors initiated with contraction and labors initiated with a spontaneous rupture of membranes. Moreover, the obtained results represent evidence of gradual disruption of rhythmicity from mild to extreme prematurity.

Can the Day of the Week and the Time of Birth Predict the Mode of Delivery According to Robson Classification?

Worldwide, the cesarean section rate has steadily increased from 6.7% in 1990 to 21.1% in 2018 and is expected to rise even more. The World Health Organization propose the adoption of the Robson classification system as a global standard for monitoring, evaluating, and comparing delivery rates. The purpose of the current study is to use the Robson classification system to investigate how, independently of medical factors, the day of the week and time of delivery may be related to the mode of birth. In the sample analysis, we included the records of 8572 women giving birth in one private health facility in Greece. Over 60% of deliveries during the study period were performed by cesarean section, 30.6% by vaginal delivery, and 8.5% of deliveries were performed by operative vaginal delivery. The results of this study indicate that the lowest birth rates are observed on Monday, Saturday, and Sunday. Nulliparous women with no previous cesarean delivery, with a singleton in cephalic presentation ≥37 weeks with spontaneous labor (group 1) are 73% more likely to deliver by cesarean section between 08:00 A.M. and 03:59 P.M. compared to those who give birth between 12:00 A.M. and 07:59 A.M. Also, multiparous women with a single cephalic term pregnancy and one previous cesarean section (group 5.1) are 16.7 times more likely to deliver by cesarean section in the morning compared to overnight deliveries. These results point out two non-clinical variables that influences the CS rate. The Robson classification system was a useful tool for the above comparisons.

Temporal patterns of weekly births and conceptions predicted by meteorology, seasonal variation, and lunar phases

Background

Data reporting the number of births given by women resident in Vienna for each week between 1999 and 2019, and the duration (in weeks) of their pregnancies, were used to estimate the week of conception. When preliminary examinations detected cyclical patterns for births and conceptions, a series of Poisson regressions for births and conceptions were performed to assess whether these cycles could be associated with lunar or solar phases.

Methods

To that end 2 sine-cosine functions, 1 with a wavelength of 1 year (365.25 days) and 1 with a wavelength of 29.529 days, the latter resembling the average length of a lunar cycle, were constructed. In addition, also average weekly temperatures were included in the models.

Results

Same week temperature was a strong non-linear predictor for both births and conceptions. Extreme temperatures, especially hot temperatures, increased the number of births while the numbers of successful conceptions were decreased by extreme temperatures. Regarding annual variation in conceptions, the lowest values were found in May and the highest in late autumn and early winter. Therefore, the highest numbers of births are observed in the summer. As per lunar variations, the highest numbers of conceptions occurred at the full moon and the highest numbers of births at the waxing crescent to first quarter moon.

Discussion

The latter results should be treated with caution, as they are not hypothesis driven. Furthermore, literature reports on this topic are conflicting. Nevertheless, these findings will be useful in further analyses examining air pollution effects.

The thermal consequences of primate birth hour and its evolutionary implications

Most primates, including humans, give birth during the inactive phase of the daily cycle. Practical constraints therefore limit our knowledge of the precise timing of nocturnal birth in wild diurnal primates and so limit our understanding of selective pressures and consequences. We measured maternal core body temperature (T_b) across 24 births in a population of wild vervet monkeys using biologgers. We identified distinct perturbations in T_b during the birth period, including declining T_b during labour and the rapid recovery of T_b post-parturition. Vervet monkeys typically gave birth during their inactive phase in synchrony with the nadir of the maternal nychthemeral T_b rhythm but also showed remarkable inter-individual variability in their absolute T_b during birth. Our findings support the view that selection may have favoured a nocturnal timing of primate birth to coincide with lower night-time T_b and environmental temperatures, which improve thermal efficiency during birth.

Male and female birth attendance and assistance in a species of non-human primate (Rhinopithecus bieti)

Birth attendance, or midwifery service, is an important characteristic in human evolution, and has been argued to separate our lineage from other taxa in the animal kingdom. Recent studies, however, indicate that similar or analogous behaviors also may occur in a small number of nonhuman primate species. Here, we report the first case of both male and female attendance and female birth assistance in a wild species of nonhuman primate, the black-and-white snub-nosed monkey (Rhinopithecus bieti). At our field site in Yunnan, China we observed a diurnal birth event in which the leader male of a one-male unit (OMU) remained in close- proximity (0-2 m) to the parturient, groomed her, and remained vigilant over a five hour pre- and postpartum period. In addition, a multiparous female member of the OMU also remained in close proximity to the soon-to-be mother, helped to pull the neonate from the birth canal, took the neonate from the new mother within 15 s of the birth, held the infant for 20 min, and then severed the umbilical cord. For the next several days the leader male traveled in close-proximity to the new mother and four days after the birth event, we observed him to share food with her. Given that diurnal births are extremely rare in this primate species; it remains unclear the degree to which the events we observed commonly occur during nighttime births. We argue that adult male and female black-and-white snub-nosed monkeys are highly attracted to young infants, and birth attendance and birth assistance in this, and certain other primate species, may play a critical role in maternal and infant survivorship.

Childbirth care for adolescents and advanced maternal age in maternities linked to Rede Cegonha

Based on the Rede Cegonha guidelines that propose the strengthening of women's sexual and reproductive rights, we sought to present a brief overview of issues related to reproductive planning and to analyze obstetric practices in childbirth care for adolescents and women of advanced age in maternity hospitals linked to Rede Cegonha. Data were extracted from an assessment conducted in 2017, based on information from the interview with puerperal women and from the hospital record. For age extremes, the high proportion of unplanned pregnancies and low use of contraception means problems in accessing family planning programs. Adolescents are more exposed to the presence of a companion and less to the use of analgesia in labor. Advanced maternal age were more likely to use analgesia in labor and to give birth in the lithotomy position, being less exposed to amniotomy. Although Rede Cegonha is an excellent strategy for improving assistance to childbirth, attention is still needed to the use of potentially unnecessary or not recommended interventions, with greater incentive to good obstetric practices.

Non-Clinical Variables Influencing Cesarean Section Rate According to Robson Classification

Background and Objectives: The incidence of cesarean section (CS) has progressively increased worldwide, without any proven benefit to either the mother or the newborn. The aim of this study was to evaluate the association between CS rates and both clinical and non-clinical variables, while applying the Robson classification system. Materials and Methods: This is a retrospective observational study of pregnant women delivering at a tertiary care hospital between 2012 and 2017, either under public or private healthcare. The overall CS rate, and the elective and non-elective CS rate, divided by classes of Robson, were determined. The rate of vaginal deliveries and CSs was compared between the public and private setting. The distribution of incidence of non-elective CSs and their main indications were analyzed between daytime and nighttime. Results: 18,079 patients delivered during the study period: 69.2% delivered vaginally and 30.8% by CS. Robson class 5 was the most frequent (23.4%), followed by class 2B (16.8%). Of the 289 private practice deliveries, 59.2% were CSs. The CS rate was significantly higher in private compared to public practice: 59.2% and 30.4%, respectively (OR 3.32, 95% CI 2.62 ± 4.21). When only considering elective CSs, a statistically significant difference was found in Robson class 5 between private and public practice, with the latter having more CSs (94.2% and 83.8%, respectively (p = 0.046)). The rate of non-elective CS was significantly lower during nighttime than during daytime (17.2% vs. 21.5%, p < 0.01). During daytime, the higher incidence of CS occurred between 4:00 and 4:59 pm, and during nighttime between 9:00 and 9:59 pm. Failed induction was significantly more common as an indication to CS during daytime when compared to nighttime (p = 0.01). Conclusions: This study identified two non-clinical variables that influenced the CS rate: the type of healthcare setting (private vs. public) and the time of the day. We believe that these indications might be related more to the practitioner attitude, rather than objective delivery complications.

Revisiting the effect of time of birth on neonatal, infant, and child mortality in rural Spain, 1830-1929

OBJECTIVES

This article aims to determine whether different patterns of mortality occurred among children born during the day and the night respectively, between 1830 and 1929.

METHODS

The data include the time of birth and death of 9814 individuals from 10 villages in rural Spain between 1830 and 1929, within a context of natural births at home with little medical support. These data were subjected to a comparative analysis relating to the time of birth and the age at death.

RESULTS

Neonatal, infant, and child mortality was higher for children born during daytime. The day-to-night mortality pattern diverged until children were at least 5 years old.

CONCLUSIONS

The results confirm that the mortality patterns differed according to the time of birth. Possibly some of these children experienced longer or problematic deliveries that, in the absence of good medical assistance, had health consequences during the following days and years of life.

Births and their outcomes by time, day and year: a retrospective birth cohort data linkage study

Background

Studies of daily variations in the numbers of births in England and Wales since the 1970s have found a pronounced weekly cycle, with numbers of daily births being highest from Tuesdays to Fridays and lowest at weekends and on public holidays. Mortality appeared to be higher at weekends. As time of birth was not included in national data systems until 2005, there have been no previous analyses by time of day.

Objectives

To link data from birth registration and birth notification to data about care during birth and any subsequent hospital admissions and to quality assure the linkage. To use the linked data to analyse births and their outcomes by time of day, day of the week and year of birth.

Design

A retrospective birth cohort analysis of linked routine data.

Setting

England and Wales.

Outcome measures

Mortality of babies and mothers, and morbidity recorded at birth and any subsequent hospital admission.

Population and data sources

Birth registration and notification records of 7,013,804 births in 2005–14, already linked to subsequent death registration records for babies, children and women who died within 1 year of giving birth, were provided by the Office for National Statistics. Stillbirths and neonatal deaths data from confidential enquiries for 2005–9 were linked to the registration records. Data for England were linked to Hospital Episode Statistics (HES) and data for Wales were linked to the Patient Episode Database for Wales and the National Community Child Health Database.

Results

Cross-sectional analysis of all births in England and Wales showed a regular weekly cycle. Numbers of births each day increased from Mondays to Fridays. Numbers were lowest at weekends and on public holidays. Overall, numbers of births peaked between 09.00 and 12.00, followed by a much smaller peak in the early afternoon and a decrease after 17.00. Numbers then increased from 20.00, peaking at around 03.00–05.00, before falling again after 06.00. Singleton births after spontaneous onset and birth, including births in freestanding midwifery units and at home, were most likely to occur between midnight and 06.00, peaking at 04.00–06.00. Elective caesarean births were concentrated in weekday mornings. Births after induced labours were more likely to occur at hours around midnight on Tuesdays to Saturdays, irrespective of the mode of birth.

Limitations

The project was delayed by data access and information technology infrastructure problems. Data from confidential enquiries were available only for 2005–9 and some HES variables were incomplete. There was insufficient time to analyse the mortality and morbidity outcomes.

Conclusions

The timing of birth varies by place of birth, onset of labour and mode of birth. These patterns have implications for midwifery and medical staffing.

Future work

An application has now been submitted for funding to analyse the mortality outcomes and further funding will be sought to undertake the other outstanding analyses.

Funding

This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full inHealth Services and Delivery Research; Vol. 7, No. 18. See the NIHR Journals Library website for further project information.

Timing of singleton births by onset of labour and mode of birth in NHS maternity units in England, 2005-2014: A study of linked birth registration, birth notification, and hospital episode data

BACKGROUND

Maternity care has to be available 24 hours a day, seven days a week. It is known that obstetric intervention can influence the time of birth, but no previous analysis at a national level in England has yet investigated in detail the ways in which the day and time of birth varies by onset of labour and mode of giving birth.

METHOD

We linked data from birth registration, birth notification, and Maternity Hospital Episode Statistics and analysed 5,093,615 singleton births in NHS maternity units in England from 2005 to 2014. We used descriptive statistics and negative binomial regression models with harmonic terms to establish how patterns of timing of birth vary by onset of labour, mode of giving birth and gestational age.

RESULTS

The timing of birth by time of day and day of the week varies considerably by onset of labour and mode of birth. Spontaneous births after spontaneous onset are more likely to occur between midnight and 6am than at other times of day, and are also slightly more likely on weekdays than at weekends and on public holidays. Elective caesarean births are concentrated onto weekday mornings. Births after induced labours are more likely to occur at hours around midnight on Tuesdays to Saturdays and on days before a public holiday period, than on Sundays, Mondays and during or just after a public holiday.

CONCLUSION

The timing of births varies by onset of labour and mode of birth and these patterns have implications for midwifery and medical staffing. Further research is needed to understand the processes behind these findings.

Cesarean section and the manipulation of exact delivery time

Physicians are often alleged responsible for the manipulation of delivery timing. We investigate this issue in a setting that negates the influence of financial incentives on physician's behavior. Working on a sample of women admitted at the onset of labor in a big public hospital in Italy we estimate a model for the exact time of delivery as driven by individual Indication to Cesarean Section (ICS) and covariates. We find that ICS does not affect the day of delivery but leads to a circadian rhythm in the likelihood of delivery. The pattern is consistent with the postponement of high ICS deliveries in the late night\early morning shift. Our evidence hardly supports the manipulation of timing of births as driven by medical staff's "demand for leisure". Physicians seem to manipulate the exact timing of delivery to reduce exposure to risk factors extant during off-peak periods.

Does Time of Delivery Influence the Risk of Neonatal Morbidity?

OBJECTIVE

To examine whether time of delivery influences the risk of neonatal morbidity among women with singleton pregnancies.

STUDY DESIGN

Secondary analysis of data from the Maternal Fetal Medicine Units Network Factor V Leiden Mutation study. We categorized time of delivery as day (07:00-16:59), evening (17:00-23:59), and overnight (midnight-06:59). Severe neonatal morbidity was defined by at least one of the following: respiratory distress syndrome, transient tachypnea of the newborn, sepsis, seizures, neonatal intensive care admission, or a 5-minute APGAR ≤3. We calculated frequencies of severe neonatal morbidity by time of delivery. Multivariate analysis was performed to determine whether time of delivery was independently associated with severe neonatal morbidity.

RESULTS

Among 4,087 women, 1,917 (46.9%) delivered during the day, 1,140 (27.9%) delivered in the evening, and 1,030 (25.2%) delivered overnight. We observed no significant differences in the rates of neonatal morbidity between delivery time periods (day: 12.3%; evening: 12.8%; overnight: 12.6%; p = 0.9). No significant association was observed between time of delivery and neonatal morbidity after adjustment for maternal, obstetric, and peripartum factors.

CONCLUSION

Our findings suggest that time of delivery is not associated with severe neonatal morbidity.

Parturition and potential infanticide in free-ranging Alouatta guariba clamitans

Parturition is a key process of mammalian reproduction that is rarely documented in New World monkeys because it often occurs at night. However, diurnal births have been recorded in several species. In howler monkeys (Alouatta spp.) they have often been observed during prolonged resting periods. Similarly, infanticide is a behavior observed quite infrequently. Infanticide in howler monkeys is often inferred from infant deaths or disappearances after group takeovers by nonresident male(s). Here we report the first observation of parturition and birth-related behaviors in the brown howler monkey (Alouatta guariba clamitans) and the likely attack on the infant that caused its death. The mother was a multiparous female that lived in a ca. 3-ha Atlantic forest fragment in southern Brazil with nine group mates. The behavior ("all occurrences") sampling method was used to record birth-related behaviors and social interactions. The parturition occurred during the day of 27 October 2013 during a feeding session. The female showed no sign of contraction or birth delivery posture. Parturition began apparently after matrix rupture and release of the amniotic fluid. Expulsion of the newborn occurred between 1 and 3 min later (the exact moment of delivery was not observed). Then, the female held and licked the newborn and began to ingest the placenta and the umbilical cord. The other group members continued feeding and had no interaction with the parturient during the preparturition and parturition events. The infant died ca. 35 days later as a consequence of injuries to his forehead and face, potentially caused by a conspecific bite. Because the adult and subadult males chased the female in the day that the infant's wounds were detected, we believe that one of them might have been the aggressor. We discuss this putative case of infanticide in light of the potential motivation of each male.

Revisiting the daily human birth pattern: time of delivery at Casa de Maternidad in Madrid (1887-1892)

OBJECTIVES

Among the ancestral characteristics of the primate group to which Homo sapiens belongs we find a pattern of daytime physical activity, but one notable exception is birthing which usually begins with night-time labor. In populations with a moderate or high level of medicalized labor, there is evidence that the medical preferences interfere with the underlying biological mechanism for the circadian pattern of human birth.

METHODS

This study analyses the hourly patterns of 4,599 single live births in the House of Maternity in Madrid between 1887 and 1892, a period of very limited obstetric intervention and without the influence of artificial lighting. In order to determine the influence of natural light on labor, two periods of maximum and minimum light have been established around the summer and winter solstices of the years in question.

RESULTS

A clear circadian pattern of births emerges, with very early morning and early morning births dominating, and a sharp drop from midday until nightfall. The hourly distribution on both solstices follows this pattern, but with a clear peak shift: in winter, there is a greater concentration of deliveries in the early morning, whereas in the summer, the highest concentration is between 8 and 12 in the morning.

CONCLUSIONS

The results confirm that non-intervened human birth has a clear diurnal cycle, with a higher incidence of deliveries in the early morning or morning. The shift in distribution during the winter and summer solstices seems to confirm the effect of light on the labor process.

Maternal Characteristics and Temporal Trends in Birth Outcomes: Comparison between Spanish and Migrant Mothers

Low birth weight and preterm babies have been increasing in Spain since 1980, coinciding with important changes in the social and demographic structure of childbearing populations—including the contribution of a 25% of foreign mothers—and with increasing medical intervention in births. This study, based on 5,990,613 births, compares the temporary trends in reproductive patterns and birth outcomes in Spanish and foreign mothers during the period 1996–2009 and evaluates for the years 2007 to 2009 the relative contribution of mother's origin and Caesarean section to birth weight variability. Foreign mothers maintain their own reproductive pattern, whereas negative birth outcomes increase in all groups. Results from logistic regression analysis show that besides late maternity and primiparity also Caesarean section increases the risk for low birth weight. The reduction in Caesarean section rates between 2007 and 2009 might explain the reduction of low birth weight detected. A change of tendency simultaneously appears in most maternal and newborn characteristics, and in the mode of delivery in all ethnic groups since 2008. Coincidence in the timing of the change of trends points to a common factor. We suggest that the current world financial crisis could be this common cause, a hypothesis to be contrasted in future research.