MATERNAL AND CHILD HEALTH BRIEF #3: INFANT MORTALITY, LOW BIRTH WEIGHT AND PRETERM BIRTH OCTOBER 2012 INFANT MORTALITY, OVERVIEW LOW-BIRTH WEIGHT AND PREMATURITY DEFINED Infant Mortality An infant death is defined as death before one year of age. Infant deaths are typically examined as rates, or in any given year, the total number of infants who die before one year of age divided by all live born infants in that year. The infant mortality rate is an indicator of the health status of a country, state, or community.i This Maternal and Child Health (MCH) Brief summarizes the latest data regarding three key Low Birth Weight indicators of birth outcomes - the rates of infant Low birth weight babies weigh less than 2500 mortality, low birth weight and preterm birth. The grams (5 pounds, 8 ounces) at birth. Low birth brief also identifies several strategies in terms weight may be subdivided into very low birth of promotion and prevention that are thought to weight (less than 1500 grams) and extremely be effective in raising awareness and educating low birth weight (less than 1000 grams). At women and families about the issues and risk the population level, the proportion of babies factors related to these three suboptimal birth with a low birth weight is an indicator of public outcomes. Finally, the brief discusses the public health problems including long-term maternal health role from the perspective of Maternal and malnutrition, ill health, hard work and poor health Child Health programs in promoting health across care in pregnancy. On an individual basis, low the lifespan and preventing infant mortality, low birth weight is an important predictor of newborn birth weight and preterm birth. health and survival.ii (continued on page 2) MATERNAL AND CHILD HEALTH BRIEF #3: 1 INFANT MORTALITY, LOW-BIRTH WEIGHT, AND PREMATURITY (CONTINUED) Preterm Birth Preterm birth is defined as birth occurring at less than 37 completed weeks gestation. LOW BIRTH WEIGHT TRENDS The American College of Obstetricians and In the five year period 1998-2002, 9% of births Gynecologists subdivides preterm birth into in Delaware consisted of infants with low birth extremely preterm (< 28 weeks), early preterm weight (2,500 grams or less). Since this period (28-31 weeks), moderately preterm (32-33 the percentage of low birth weights has risen to weeks), and late preterm (34-36 weeks). a high of 9.4% and returned to a rate of 9% in Preterm birth is also an important predictor of the five year period 2005-2009. Nationally, the newborn health and survival.iii percentage of low birth weight births has ticked upward from 7.6% in the period of 1998-2002 to iv 8.2% in the period of 2004-2008 (Figure 4). INFANT MORTALITY TRENDS Although Delaware’s infant mortality rate Five Year Average Percentage of Low Birth Weight Five Year Average Percentage of is above the national average, the gap has Births,Low Delaware Birth Weight Births,and the United states Delaware and the United States 10 9 been narrowing over the last decade. For the Births 8 7 6 5 five year period 2001-2005, Delaware’s infant grams) Birthweight United States 4 Low Delaware 3 2,500 of (< 2 1 mortality rate was 9.3 deaths per 1,000 live 0 1998‐ 1999‐ 2000‐ 2001‐ 2002‐ 2003‐ 2004‐ 2005‐ Percentage 2002 2003 2004 2005 2006 2007 2008 2009* United States 7.6 7.7 7.8 7.9 8 8.1 8.2 births compared to a national average rate of Delaware 9 9.2 9.3 9.4 9.4 9.3 9.1 9 *Data for the U.S. are not available for 2005‐ 2009. 6.9 deaths per 1,000 live births. For the five year FIG.4 period 2005-2009, Delaware’s infant mortality rate was 8.3 deaths per 1,000 live births Among the state’s three counties, the highest compared to 6.6 deaths per 1,000 live births percentages of low birth weight births over the nationally. The overall decrease in the rate in last decade have been in New Castle County Delaware (10.7%) was over twice the decrease where the percentage has varied between in the national rate (4.3%) over this period 9.5% and 9.9%. For the latest five year period (Figure 1).iv available (2005-2009), the percentage of low birth (continued on page 3) weight births in New Castle County was 2 MATERNAL AND CHILD HEALTH BRIEF #3: INFANT MORTALITY TRENDS (CONTINUED) Despite the relative decline in overall infant mortality in the state, the disparity ratio (comparing Five Year Infant Mortality Rates, DelawareFive Year Infantand the Mortality United Rates,States Delaware and the United States the rate of deaths of black infants to the rate 10 9 Births 8 of deaths to white infants) was higher than the Live 7 6 1,000 United States 5 national disparity ratio and ticked upwards in the per 4 Delaware 3 Deaths iv 2 2005-2009 five year period (Figure 3). 1 Infant 0 1998‐ 1999‐ 2000‐ 2001‐ 2002‐ 2003‐ 2004‐ 2005‐ 2002 2003 2004 2005 2006 2007 2008 2009 United States 7 6.9 6.9 6.9 6.8 6.8 6.7 6.6 Delaware 9.2 9.1 9.3 9.3 8.8 8.6 8.4 8.3 Five Year Average Infant Mortality Disparity Ratio (Black InfantFive MortalityYear Average InfantRate/ Mortality White Disparity Infant Ratio Mortality Rate) FIG.1 (Black Infant Mortality Rate / White Infant Mortality Rate) DelawareDelaware and and the the United United States states 3.0 2.5 Ratio In terms of geographic differences, Kent County, 2.0 Disparity 1.5 United States once the county with the highest infant mortality Delaware Mortality 1.0 rate (10.2 deaths per 1,000 live births) in the five Infant 0.5 0.0 1998‐ 1999‐ 2000‐ 2001‐ 2002‐ 2003‐ 2004‐ 2005‐ year period 2000-2004, has improved to a rate 2002 2003 2004 2005 2006 2007 2008 2009 United States 2.5 2.5 2.5 2.5 2.4 2.4 2.4 2.4 Delaware 2.4 2.4 2.2 2.5 2.5 2.5 2.5 2.7 FIG.3 of 7.1 deaths per 1,000 live births in the five year period 2005-2009. It should be noted that in terms of overall burden of infant mortality rate, the City LOW-BIRTH WEIGHT (CONTINUED) of Wilmington appears to be a driving factor in 9.5 percent. Conversely, Sussex county has New Castle County’s rates (as well as statewide). consistently had the lowest percentages of low For the five year period 2005-2009, the infant birth weight births over the same time period with mortality rate in the City of Wilmington was 13.8 7.8% of births reported to be low birth weights in deaths per 1,000 live births compared to 8.0 infant the five year period 2005-2009 (Figure 5).iv deaths per 1,000 live births in the balance of New Delaware Five Year Average Percentages of Low Birth Weight Births iv Delaware Five Year Average Percentages of Low Birth Castle County (Figure 2). Weight(< 2,500 Births grams) (<2,500 by County grams) by County 12 Births 10 8 Kent Delaware Five Year Infant Mortality Rates New Castle Delaware Five Year Infant Mortality Rates by County 6 grams) Birthweight by County Sussex 4 Low 12 2,500 of (< 2 Births 10 Live 0 8 1998‐ 1999‐ 2000‐ 2001‐ 2002‐ 2003‐ 2004‐ 2005‐ Kent Percentage 2002 2003 2004 2005 2006 2007 2008 2009 1,000 6 New Castle Kent 8.9 9.2 9.3 9.5 9.3 9.3 9 8.8 per 4 Sussex New Castle 9.3 9.6 9.7 9.9 9.9 9.8 9.6 9.5 Sussex 7.9 8 8 7.8 8 7.8 7.7 7.8 Deaths 2 Infant FIG.5 0 1998‐ 1999‐ 2000‐ 2001‐ 2002‐ 2003‐ 2004‐ 2005‐ 2002 2003 2004 2005 2006 2007 2008 2009 Kent 9.9 9 10.2 10 9.1 7.1 7.1 7.1 New Castle 9.2 9.5 9.4 9.4 9.2 9.2 9.0 9.0 Sussex 8.3 7.4 8.1 8.2 7.5 7.9 7.6 7.2 (continued on page 4) FIG.2 MATERNAL AND CHILD HEALTH BRIEF #3: 3 LOW BIRTH WEIGHT (CONTINUED) Five Year Average Low Birth Weight Disarity Ratio (Black Low FiveBirthweight Year Average LowPercentage Birth Weight Disparity/ White Ratio Low Birthweight (Black Low Percentage)Birthweight Percentage Delaware / White Lowand Birthweight the United Percentage) States The association of low birth weight with infant Delaware and the United States mortality can be better understood by examining 2.1 Ratio 2.0 1.9 US the infant mortality rate among assorted birth Disparity 1.8 Delaware 1.7 Weight weight ranges. For infants who are born at 1.6 Birth 1.5 1998‐ 1999‐ 2000‐ 2001‐ 2002‐ 2003‐ 2004‐ 2005‐ Low 2002 2003 2004 2005 2006 2007 2008 2009* *Data for the U.S. are a weight of 2,500 grams or more, the infant not available for 2005‐ US 2.0 2.0 1.9 1.9 1.9 1.9 1.9 2009. Delaware 1.91.91.91.91.91.91.91.9 mortality rate for the five year period 2004-2008 FIG.7 was 1.9 deaths per 1,000 live births. Among infants born at a birth weight of between 1,500 grams and 2,499 grams, the infant mortality rate was 13.8 PRETERM BIRTHS BY deaths per 1,000 live births.