‘Artificial womb’ improves premature babies’ survival
*Low-cost drug reduces death due to bleeding in women with post-partum haemorrhage
*Miscarriage risk may be higher with use of common antibiotics, researchers find
A unique womb-like environment designed by pediatric researchers could transform care for extremely premature babies, by mimicking the prenatal fluid-filled environment to give the tiniest newborns a precious few weeks to develop their lungs and other organs.
“Our system could prevent the severe morbidity suffered by extremely premature infants by potentially offering a medical technology that does not currently exist,” said study leader Alan W. Flake, MD, a fetal surgeon and director of the Center for Fetal Research in the Center for Fetal Diagnosis and Treatment at Children’s Hospital of Philadelphia (CHOP), United States (US).
Flake and colleagues report on preclinical studies of their extra-uterine support device in Nature Communications. They tested and monitored effects on fetal lambs, in which prenatal lung development is very similar to that occurring in humans.
The innovative system uses a unique fluid-filled container attached to custom-designed machines that provide physiologic support. The fetal lambs grow in a temperature-controlled, near-sterile environment, breathing amniotic fluid as they normally do in the womb, their hearts pumping blood through their umbilical cord into a gas exchange machine outside the bag. Electronic monitors measure vital signs, blood flow and other crucial functions.
Of the one in ten U.S. births that are premature (younger than 37 weeks gestational age), about 30,000 per year are critically preterm-younger than 26 weeks. Extreme prematurity is the nation’s leading cause of infant mortality and morbidity, accounting for one-third of all infant deaths and one-half of all cases of cerebral palsy attributed to prematurity.
Neonatal care practices have improved overall survival of premature infants and have pushed the limits of viability to 22 to 23 weeks of gestation. At that age an infant weighs below 600 grams— little more than a pound—and has a 30 to 50 percent chance of survival. But this survival comes at a high price in quality of life, with a 90 percent risk of morbidity, from chronic lung disease or other complications of organ immaturity. Survivors face lifelong disability.
“These infants have an urgent need for a bridge between the mother’s womb and the outside world,” said Flake. “If we can develop an extra-uterine system to support growth and organ maturation for only a few weeks, we can dramatically improve outcomes for extremely premature babies.” The goal is to support infants from 23 weeks to 28 weeks gestational age; at 28 weeks they cross the threshold away from the most severe outcomes.
In the current study, the researchers describe the evolution of their system over three years, through a series of four prototypes, beginning with a glass incubator tank, and progressing to the current device. The eight preterm lambs tested in the most recent prototype were physiologically equivalent to a 23- or 24-week-gestation human infant. The current system mimics life in the uterus as closely as possible, building on knowledge from previous neonatal research. There is no external pump to drive circulation, because even gentle artificial pressure can fatally overload an underdeveloped heart, and there is no ventilator, because the immature lungs are not yet ready to do their work of breathing in atmospheric oxygen. Instead, the baby’s heart pumps blood via the umbilical cord into the system’s low-resistance external oxygenator that substitutes for the mother’s placenta in exchanging oxygen and carbon dioxide.
Meanwhile, tranexamic acid – an inexpensive and widely available drug – could reduce maternal deaths among women with severe bleeding after child birth, according to a global trial of 20,000 women in 21 countries, published in The Lancet. The study found that death due to bleeding was reduced by a third if the drug was given within three hours of the onset of post-partum haemorrhage.
Post-partum haemorrhage (severe bleeding after child birth) is the leading cause of maternal death worldwide, responsible for 100,000 deaths per year, 99 per cent of which occur in low and middle income countries. The time from the onset of post-partum haemorrhage to maternal death can sometimes be only a few hours.
Tranexamic acid works by stopping fibrinolysis (the breakdown of blood clots), a process that can occur in trauma or soon after child birth. Previous research has shown that tranexamic acid reduces death due to bleeding in trauma patients.
Current World Health Organisation (WHO) guidelines recommend the use of tranexamic acid in post-partum haemorrhage if uterotonics (drugs to induce contractions) fail to control the bleeding, or if the bleeding is thought to be due to trauma2. The findings from the trial suggest that the drug should be given as soon as possible after the onset of post-partum haemorrhage, at the same time as uterotonics.
“We now have important evidence that the early use of tranexamic acid can save women’s lives and ensure more children grow up with a mother. It’s safe, affordable and easy to administer, and we hope that doctors will use it as early as possible following the onset of severe bleeding after childbirth,” says Associate Professor Haleema Shakur, London School of Hygiene & Tropical Medicine (UK) who led the trial.
The WOMAN (World Maternal Antifibrinolytic) trial included over 20,000 women aged 16 or over in 193 hospitals in 21 countries, mostly in Africa and Asia.
Women diagnosed with post-partum haemorrhage after a vaginal birth or caesarean section were randomised to receive either 1g of intravenous tranexamic acid or placebo, in addition to usual care. If bleeding continued after 30 minutes, or stopped and restarted within 24 hour of the first dose, a second dose was given.
Also, a new study suggests that guidelines for antibiotic use during early pregnancy might need to be reviewed, after finding that some common classes of the drug could double the risk of miscarriage.
Researchers from the University of Montreal in Canada have identified a link between the use of macrolides, quinolones, tetracyclines, and some other common antibiotics in early pregnancy and an increased risk of miscarriage.
The findings were recently reported in the Canadian Medical Association Journal. Miscarriage is defined as the spontaneous loss of a fetus before 20 weeks of pregnancy.
According to the Eunice Kennedy Shriver National Institute of Child Health and Human Development, miscarriage occurs in around 15 to 20 percent of women who are aware of their pregnancy, and it is most common among women aged 35 or older.
Over half of all miscarriages are caused by abnormalities in the chromosomes of the fetus. Other factors that may raise the risk of miscarriage include diabetes, polycystic ovary syndrome, obesity, and infection.
Study co-author Dr. Anick Bérard, of the Faculty of Pharmacy at the University of Montreal, notes that antibiotics are widely used during pregnancy to help treat infection, but studies assessing their safety have produced conflicting results.
While previous studies have identified a link between antibiotic use in pregnancy and risk of miscarriage, the researchers note that these studies have a number of limitations, such as small samples and recall bias.