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Fewer premature babies born during pandemic: mystery discussed in NYT article July 19


photo of a great-grandson by Mary Molina, copyright reserved

I have previously posted about the odd changes in emergency room visits that have occurred as a result of the pandemic.  Normal emergency cases have suddenly disappeared; drops in heart attacks, strokes, appendicitis, car crashes, and other “normal” (expected) incidents have been observed.  One thing that had not been remarked before is the disappearance of premature babies.

This article in the New York Times of July 19 details the drop in premature deliveries that has occurred in many hospitals since the pandemic began.  The article begins with the observations of a doctor in Ireland.

According to the Times article, Dr. Roy Philip, a neonatologist at University Maternity Hospital Limerick in Ireland, noticed this when he first returned to his hospital in March at the onset of the lockdown.  He found that demand for a milk replacement used by premature babies had vanished.  When he ran the numbers, he found that premature births had dropped to a quarter of the average from previous years.

He published the results of his observations in MedRxiv as a “preprint” (not yet peer reviewed) report: compared to a historical rate of 8.18 (95% CI: 7.21, 9.29) per 1000 live births from January to April 2001 to 2019, 2.17 per 1000 live births was observed in January to April 2020. The rate ratio of 3.77 (95% CI: 1.21, 11.75), p = 0.022, represented a 73% reduction.

A Danish group reported similar results in MedRxiv on May 22.  There, a registry of 31,180 live singleton infants born in Denmark between March 12, and April 14, from 2015 to 2020 was evaluated.  “The extremely premature birth rate during the lockdown was significantly lower than the corresponding mean rate for the same dates in the previous years (odds ratio 0.09 [95 % CI 0.01 – 0.04], p < 0.001).”  That is, a greater than 90% reduction in very premature births was seen.

Doctors in Rotterdam, Melbourne, and Alberta reported similar drops.  The Times article continues, “In the United States, Dr. Stephen Patrick, a neonatologist at Vanderbilt Children’s Hospital in Nashville, estimated there were about 20 percent fewer NICU babies at his hospital than usual in March.”

The article states that not all hospitals have seen the same drop, although examples were not provided.

The causes for this dramatic drop during the last six months are unknown as yet.  It is not even clear whether the drop is localized or general.  Explanations could include reduction in air pollution, imposition of reduced activity outside the home, or many other changes unique to the lockdown.  Whatever the reason, this is a fascinating finding and will certainly stimulate a lot of research.

Trends in premature birth in prior years:

In the US, premature deliveries have increased for the last four years in a row, according to the CDC.  “White women had about a 9 percent risk of premature birth in 2018, while African-American women’s risk was 14 percent.”  According to Statista, premature births in the US increased from 10.62% in 1990 to 12.8% in 2006, but then suddenly dropped to 10.4% in 2007 (perhaps a change in definition?  It’s not clear.)

The overall birth rate dropped from 16.7 per 1,000 people in 1990 to 11.6 per 1,000 in 2018.  That same year, there were 50 births per 1,000 women among White women and the same among Asian women.  There were 54 births per 1,000 among Black women, 55 among Latino women, 59 among Native American women, and 67 among Pacific Islander or Hawaiian women.

According to CDC, premature births and low birth weight accounted for 17% of infant deaths in 2017.

Here is some general information about premature birth that you may find interesting:

Premature babies (“preemies”) are defined as those born before 37 weeks of gestation (normal is 40 weeks) and this occurs in about ten percent overall of US deliveries.  Prematurity is more common in non-white mothers and those with fewer socioeconomic advantages.  Prematurity is one of the leading causes of death for children born to non-white American mothers.

Preemies are faced with a variety of problems, starting with low birthweight (1500 grams or less; average babies weigh 2500 grams) and including underdeveloped lungs as well as heart defects and problems related to the reasons why they are born early.  Premature infants are prone to vision and hearing problems, developmental delays, and cerebral palsy.

Premature delivery is most often heralded by amniotic sac breaking, leading to fluid leaking from the vagina.  Uterine contractions may precede of follow the loss of fluid.  Once the amniotic sac breaks, the baby must be delivered within 24 hours, or the risk of infection rises steeply.

Premature delivery is most often caused by infections including vaginitis (vaginal inflammation or infection) and systemic infections but often the underlying cause is unknown.  Risk factors for prematurity include diabetes, high blood pressure, multiple pregnancy (twins or more), overweight or underweight, air pollution, tobacco use, alcohol and drug abuse, and psychological stress.

Treatment for premature birth:

Those at risk or having premature contractions can be treated with progesterone (one of two major female hormones, the other being estrogen.)  Once delivery is inevitable, treatment with corticosteroids like dexamethasone and prednisone can improve outcomes, in part by stimulating maturation of the fetus’ lungs.

Nifedipine (normally used for blood pressure) and other drugs can reduce uterine contractions, delaying delivery.  Once the baby is born, supportive treatment by warming, skin-to-skin contact with the mother, and oxygen supplementation aid survival.  In extreme cases, it  may be necessary to intubate the newborn and provide mechanical ventilation.  Adding pulmonary surfactant (similar to detergent) to the oxygenated air greatly improves expansion of the lungs and therefore aids survival.

Complications of premature birth:

Premature birth is the most common cause of neonatal mortality; those born at 22 weeks’ gestation have about a 6% chance of survival, improving with each week after that, up to 72% at 25 weeks.  Survival is often followed by numerous complications, from acute respiratory distress syndrome due to insufficient secretion of surfactant (called hyaline membrane disease) chronic lung disease (which used to be called bronchopulmonary dysplasia), blindness (sometimes caused by oxygen toxicity), bleeding into the brain (intraventricular hemorrhage, affecting 25% of those born before 32 weeks), to hypoxic-ischemic encephalopathy (brain damage caused by lack of oxygen.)

Other problems of prematurity include anemia, low blood platelets, high ammonia, low calcium, low thyroid hormones, and high bilirubin.

Normally, the fetus has a type of hemoglobin (Hgb) which has a greater affinity for oxygen than adult Hgb (fetal Hgb.)  After birth, fetal Hgb is broken down and replaced by adult Hgb.  Breakdown of fetal Hgb increases blood bilirubin levels, and this has to be metabolized in the liver.  The newborn liver is not well equipped to do this work, and as a result, blood hemoglobin can rise rapidly.  In addition, Rh-incompatibility can cause breakdown of red blood cells.  A common and feared complication of elevated bilirubin (icterus) (signalled by yellow skin) can lead to brain damage (kernicterus) or death.

Icterus is common even in normal newborns and usually resolves spontaneously or through exposure to ultraviolet light (such as in sunlight) but if the level of bilirubin rises too high, it accumulates in the brain and kills nerve cells.  Emergency treatment of high bilirubin is by exchange transfusion, in which the blood is replaced by equal amounts of normal blood.

If the ductus arteriosus (a bypass circuit in the heart which diverts blood from the lungs during growth in the womb) doesn’t close (known as patent ductus arteriosus or PDA) over time the pressure in the right side of the heart can increase and lead to right-sided heart failure.  The earliest sign of PDA is low blood oxygen and shortness of breath.  Normally the ductus arteriosus closes shortly after birth, but preemies often fail to close the ductus. and eventually show pulmonary hypertension (high pressure on the right side of the heart) and develop right heart failure.

Long term complications:

Nearly half of survivors born at 22-25 weeks of gestation have moderate to severe disabilities, including visual or hearing loss, cerebral palsy, and learning problems.  Twelve percent have cerebral palsy and fifteen percent have hearing loss.  Only 20 percent of these children are completely free of disabilities.

The 2007 Institute of Medicine report Preterm Birth found that the 550,000 premature babies born each year in the U.S. run up about $26 billion in annual costs, mostly related to care in neonatal intensive care units, but the real tab may top $50 billion.

The youngest known survivor of premature birth was born in San Antonio, Texas in 2014.  She was born at 21 weeks 4 days and weighed 410 grams (14.4 ounces); she was attending preschool in 2018 and had a “slight speech delay” but was “otherwise normal.”   The smallest known survivor was one of twins delivered by Caesarean section at 25 weeks gestation (due to the mother’s pre-eclampsia) in 2004 and weighed 261 grams (9.2 ounces) while her twin weighed 563 grams (1 lb 3.9 oz)… both twins had to have laser eye surgery to correct visual problems but were said to be otherwise healthy… (Wikipedia)

(Any otherwise unattributed information may be found in Wikipedia; I don’t make anything up.)

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