The so-called weekend effect has been investigated extensively across a range of health outcomes, in a number of industrialized nations and across various disciplines. The current study is the largest to investigate it within obstetrics.

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A new study shows the extent of the worrying “weekend effect” within obstetrics.

A new study, published in The BMJ, demonstrates a higher rate of complications for babies and expectant mothers admitted during the weekend.

The study looked at more than 1 million patients admitted to English hospitals over a 2-year period.

Researchers found a significant increase in a number of negative health outcomes for expectant mothers admitted to hospitals on Saturdays and Sundays.

The controversial weekend effect appears to show a negative association between the day of delivery and measures of quality and safety of maternal care.

In short, the weekend effect hypothesizes that patients admitted to hospitals during the weekend face more risks than those arriving midweek.

Because of the huge amount of factors at play, studies into this effect have generated mixed results. Disparate areas of health care have been investigated, but results have thrown up as many questions as they have answered.

Despite the range of results, some of the findings are worrying enough to merit further investigation.

For instance, a study into acute myocardial infarctions in 922,074 elderly American patients found that those who were hospitalized at the weekend had an elevated 1-year mortality rate.

Another study investigated weekend admissions in Ontario, Canada. Researchers found that weekend patients presenting with ruptured abdominal aortic aneurysms, acute epiglottitis and pulmonary embolism saw significantly higher in-hospital mortality rates than weekday admissions.

The weekend effect has been investigated within obstetrics previously, but studies to date have produced conflicting results. This latest study, the most comprehensive to date, set out to have a thorough look at this troublesome phenomenon.

The research team, from Imperial College London, delved into the details of 1,332,835 deliveries and 1,349,599 births within the English National Health Service between April 2010 and March 2012.

Analysis focused on the day of delivery and associated outcomes across the days of the week. It also looked at measures of quality and safety of maternity services.

Across the board, Thursdays saw the highest number of births and Sundays the fewest.

Outcomes of particular interest were perinatal mortality, (death within the first 7 days after birth), emergency re-admissions, infections, perineal tears and injuries during birth.

Results were carefully adjusted for a variety of influential factors, such as mother’s age, socioeconomic factors, ethnicity, previous cesarians, diabetes, blood pressure, pre-eclampsia, eclampsia and more.

The research team found that four of the indicators they were investigating were worse for babies born at the weekends compared with weekdays: perinatal mortality, maternal infections, injury during birth and emergency readmission of the baby within 3 days of birth.

A result that stood out particularly was the level of perinatal mortality.

During weekdays, perinatal mortality was at 6.5 per 1,000 cases; at the weekend, this increased to 7.1 per 1,000. Infections were also generated more regularly at weekends. Weekdays saw 8.2 infections per 1,000 births, while the weekend generated 8.7 per 1,000.

These increases equate to a total of 770 additional perinatal deaths per year (out of the annual total of around 4,500) and 470 additional maternal infections yearly.

The number of emergency readmissions also increased over the weekend. Saturdays and Sundays saw 12.3 per 1,000, compared with 11.8 per 1,000 during the week.

Prof. Paul Aylin, from the School of Public Health at Imperial College, London, the senior academic on the team, says:

In our paper we tried to account for the fact that differences in rates of complications on different days may be due to chance, or that births on certain days are more complicated in some way.

However, even after making these adjustments, we found the rates of complications vary on different days.”

The team found no correlation between consultant staffing levels in labor wards and perinatal death or injuries during birth.

The only negative outcome with an association to consultant staffing levels was perineal tears. The rate was 3.0% in wards with compliant consultant levels and 3.3% in units that were understaffed to some degree.

The authors are quick to stress that their data is from 2012, so any changes over recent years will not have been taken into account. They also make it clear that the study was observational and cannot, therefore, be used to apportion cause and effect.

The researchers suggest further work is needed “to understand what organizational factors might influence the weekend effect and to investigate centers that have reduced the disparities in access and outcome in out of hours care.”

Jonathan Snowden and Aaron Caughey, obstetrics experts in the US, explain the results as due to “capacity strain.” In other words, the performance of a clinical unit might steadily decrease once above a certain threshold of patient volume, complexity, or both.

As previously mentioned, the number of factors involved in these types of overarching effects are mindbogglingly vast. Further study, as ever, will bring us closer to teasing apart the causes of this unwanted and uninvited weekend effect.

Medical News Today recently reported on findings that obstetric delivery for low-risk pregnancies does not improve birth outcomes.