Master Class

Infant Mortality in the U.S. and Canada


However, we are far from being “the best” in the world.

Forty nations surpass the United States in infant mortality, including Singapore (2.29 per 1,000), Sweden (2.77 per 1,000), and Japan (3.26 per 1,000).

Because the U.S. and Canada are neighbors and share a border, similar economies, and comparable levels of technologic sophistication, it is of interest that Canada's infant mortality is 30% lower than that of the United States, which was estimated by the CIA to be 6.5 per 1,000 in 2004.

In 2002, infant mortality worsened slightly in both countries, prompting renewed scrutiny of an ever-important issue.

The Centers for Disease Control and Prevention reported that in 2002, U.S. infant mortality edged upward to 7.0 per 1,000 live births from 6.8 per 1,000 in 2001.

This represents the first rise in 44 years. However, even if this anomaly were a one-time occurrence, it's concerning to note this 0.02% increase when we view the statistic in the context of more than 4 million births.

The same trend occurred in Canada, where infant mortality rose from 5.2 per 1,000 in 2001 to 5.4 per 1,000 in 2002, after progressively falling since the 1960s.

There are numerous factors that may help to elucidate this trend. At the very least, this upturn in infant mortality indicates that perhaps we are not progressing at a pace that many believe is one of the most important measures of a nation's health.

Infant mortality can be divided into two categories: neonatal deaths occurring within the first month of life, and postneonatal deaths occurring later in the first year.

Postneonatal deaths have not increased. In fact, tremendous advances in the etiology and prevention of sudden infant death syndrome have substantially reduced postneonatal deaths over the past decade.

The neonatal increases noted in 2002—and the disparity between the United States' and Canada's infant mortality—have occurred in the early weeks of life, when the most common causes of death include congenital anomalies, problems of transition, and complications of preterm birth. Among these factors, preterm birth stands out as a significant contributor to rising infant mortality.

In the United States, preterm births increased to 12.1%, from 11.9% the previous year.

Although the preterm birth rate also rose slightly in Canada, it was 7.6% in 2002—nearly 40% lower than in the United States.

Why is the preterm birth rate trending upward?

The evidence suggests that the trend is being driven by the use of reproductive technology, leading to multiple births; by women giving birth at later ages; by the necessity of earlier obstetrician intervention when the fetus is in jeopardy; and by complications attributed to a lack of early, consistent prenatal care.

The attempt to save an infant via early delivery has allowed many preemies to live who might have been stillborn in years past.

The recent changes in social trends have influenced the ages at which women decide to have their children. In Ottawa, where I practice, over 60% of mothers in 2003 gave birth when they were older than 30 years, and 23.2% when they were older than 35 years. Although women have a right to be informed about their chances of conceiving and delivering healthy singletons at different ages, physicians have no desire to dictate social policy or individual choice. I have a 5-year-old, and I'm not a young man.

We understand that older women have a higher risk of having a preterm baby, in part because they have a higher risk of having multiples, having pregnancy complications, and having babies with congenital anomalies, three factors that contribute to infant mortality.

Older mothers also are more likely to require assisted reproductive technology (ART).

Although ART procedures are similar in the United States and Canada, and are basically patient-funded in both countries, reproductive technology is increasingly subject to oversight in Canada. A bill that recently passed both the House of Commons and the Senate would strictly regulate clinics and procedures, for example.

A great many ART centers in Canada are university-affiliated, not-for-profit programs, rather than independent clinics. As a result, a controversial issue—such as the implantation of multiple embryos—is debated within the wide academic community of endocrinologists, ob.gyns., neonatologists, pediatricians, and ethicists.

When three sets of quadruplets were born in 1 year at the University of Ottawa, the university-affiliated fertility center demonstrated its responsibility by revising its policies to limit the number of embryos transferred during each cycle. Today, we rarely see quadruplets, although triplets are still not a rarity.

Throughout Canada, rates of multiple birth are lower than in the United States, contributing to lower rates of preterm birth. However, in looking at overall preterm birth statistics, it is worth noting that both nations have unequal rates across populations.

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