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Reproductive and Birth Outcomes

Stetherscope on a pregnant women's stomach

There were more than 73,000 births to Massachusetts mothers in 2010.  Most pregnancies result in a healthy baby.  A healthy baby comes from a combination of factors, including a mother's healthy diet, good prenatal care, and a safe environment where you live and work.  Researchers, The March of Dimes, and other organizations have identified a number of environmental factors that can make getting pregnant more difficult or directly cause health problems in a baby and even fetal or infant death.  Examples are exposure to lead from paint chips and paint dust in homes built before 1978; drinking water contaminants, such as disinfection byproducts; carbon monoxide; and air pollution, such as PM2.5.

Data on births are based on information from the Massachusetts Registry of Vital Records and Statistics. Medical data, such as birth weight and gestational age, are based on information supplied by hospitals and birthing facilities.  Demographic and behavioral data, such as race and ethnicity and smoking during pregnancy, are supplied by the women who gave birth. 

Did You Know?

Your health care professional can help you identify environmental exposures that you may be exposed to and learn how to minimize exposure.

The tracking of different types of reproductive outcomes by community and other geographic areas can help identify where reproductive health problems may exist and where health service needs may be greater.  It also can give clues to possible causes of adverse reproductive outcomes.

Fertility

Fertility refers to the ability to have live children and is measured by the total fertility rate.

Changes in the geographic pattern of fertility rates can provide basic descriptive clues into how environmental exposures may influence the changing patterns. As more information is learned about the potential link between environmental exposures and fertility, educational outreach programs and other interventions can target these populations to help eliminate environmental exposures that may be causing low fertility rates.

Risk factors associated with a woman's infertility include:

  • Age
  • Smoking
    Did You Know?

    One out of every six couples has trouble conceiving and/or carrying a child to term.

    Source: CDC Division of Reproductive Health 2013

  • Alcohol use
  • Being overweight or underweight
  • Too much exercise
  • Caffeine intake
  • Sexually transmitted diseases (STDs)
  • Health problems that cause hormonal changes

Environmental contaminants, including endocrine disruptors, certain solvents, phthalates, dioxin, pesticides, polychlorinated biphenyls (PCBs), and the compound benzo(a)pyrene (BaP) may be major contributors to women's infertility.

A man's health can affect fertility as well. The number produced and quality of a man's sperm can be affected by his overall health and lifestyle. Risk factors that may reduce sperm number and quality include:

  • Alcohol use
  • Illicit drug use
  • Smoking
  • Age
  • Medication
  • Radiation treatment or chemotherapy for cancer

Environmental contaminants, including pesticides (for example, dichlorodiphenyltrichloroethane or DDT), dioxin, and PCBs may be major contributors to men's infertility.

 

Data Considerations

When reviewing and interpreting fertility data, it is important to take into consideration the following:

  • The fertility measure is influenced by social/demographic choices for reproduction, maternal age, parity, and social class measures as well as the use of contraception and infertility treatments leading to multiple births. These factors all may lead to variations in overall fertility across populations and geographic locations and therefore social and demographic factors would need to be controlled for to examine any environmental effects on total fertility.
  • The total fertility rate (TFR) may not be specific enough to track specific changes related to environmental risk factors; however, this measure can be used with other measures, including measures of ambient concentrations of pollutants, to look for potential associations with population level changes in fertility and generate some well informed hypotheses or areas for future investigations.
  • The data presented are based on the location of the residence at the time of birth or death.  The place of residence or potential exposure during gestation or at the time of conception when an exposure that may have affected the outcome could have occurred, may be different.

For additional information, please read the FAQ

Available Data on Fertility

Click the Maps and Tables button on this page to access the following measure for fertility in your community. The most current available data will be shown. Be sure to check the site periodically as new data is added each year. To protect privacy, no information is shown that could identify an individual.

  • Annual total fertility rate per 1,000 women of reproductive age by community, county, and statewide

Low Birth Weight (Growth Retardation)

Baby hand laying on top of mother's hand
Did You Know?

Massachusetts is ranked 20th in percent of babies born at low birth weight.

Source: Children's Defense Fund 2013

Low birth weight occurs when the growth of the fetus is abnormally slow.  Growth retardation is measured by the number and percentage of term, singleton infants with low and very low birth weights. Low birth weight is when an infant is born with a weight less than 2,500 grams, or 5.5 pounds at birth. Very low birth weight is when an infant is born with a weight less than 1,500 grams, or 3.3 pounds at birth.

Compared to normal birth weight infants, low birth weight infants may be more at risk for:

  • Illness through the first six days of life
  • Infections
  • Long-term impairment, such as delayed motor and social development
    or learning disabilities

Exposures to lead, solvents, pesticides, and polycyclic aromatic hydrocarbons (PAHs) during pregnancy have been associated with low birth weight infants. Non-environmental risk factors include exposure to cigarette smoking (from mothers who smoke or from second-hand smoke) and no or late prenatal care.

Data Considerations

When reviewing and interpreting low birth weight data, it is important to take into consideration the following:

  • The low birth weight counts and percentages for EPHT are based on term, singleton live births only. Proportions of low birth weight births among live multiple birth categories may also be informative measures, particularly since plural births are a risk factor for prematurity, but are not considered in the EPHT measures.
  • There may be uncertainties associated with gestational age estimates due to imperfect maternal recall or misidentification of the last normal menstrual period due to post conception bleeding and/or delayed ovulation.
  • Increased low birth weight counts and percentages do not necessarily mean that environmental exposures are the cause.
  • The data presented are based on the location of the residence at the time of birth or death.  The place of residence or potential exposure during gestation or at the time of conception, when an exposure that may have affected the outcome could have occurred, may be different.

For additional information, please read the FAQ

Available Data on Low Birth Weight

Click the Maps and Tables button on this page to access the following measures for low birth weight in your community. The most current available data will be shown. Be sure to check the site periodically as new data is added each year. To protect privacy, no information is shown that could identify an individual.

  • Annual number and percent of low birth weight (less than 2,500 grams) term, singleton live births by community, county, and state
  • Average annual number and percent of very low birth weight (less than 1,500 grams) term, singleton live births by community, county, and state 

Mortality

Infant mortality occurs when an infant dies in the first year of life. Perinatal mortality is a fetal death of 28 weeks gestation or more an infant death in the first 6 days of life. Neonatal mortality is an infant death which occurs in the first 27 days of life. Postneonatal mortality is a death which occurs at 28 days up to a year of life. Mortality is measured by the mortality rate.

Identifying populations with higher perinatal, neonatal, and postneonatal mortality rates may provide leads on where to look for potential environmental problems. It will also assist in targeting outreach with educational and other interventions and improve the understanding of geographic variation, time trends, and demographic patterns of mortality.

Did You Know?

The United States infant mortality rate ranks 27th in the world (6.15 deaths per 1,000 live births).

Source: CDC, NCHS Data Brief 2013

Risk factors for mortality include:

  • Smoking
  • Substance abuse
  • Poor nutrition
  • Lack of prenatal care
  • Medical problems
  • Chronic illness
  • Sudden infant death syndrome (SIDS)
  • Air pollution (particulate matter)
Data Considerations

When reviewing and interpreting infant, neonatal, perinatal, and postneonatal mortality rate data, it is important to take into consideration the following:

  • Associations between environmental exposures and infant mortality are only one piece of a puzzle that includes many other factors such as access to and quality of health care, competency in childcare, and understanding of injury prevention.
  • It may be reasonable to assume universal reporting of live births and infant deaths in the U.S., however some births/deaths may be excluded because of the difficulty in distinguishing a death shortly after birth as a live birth; a death soon after birth might be reported as a fetal death rather than live birth and infant death.
  • The critical data for the purpose of linking deaths to environmental hazards/exposures are place of residence during pregnancy and the first year of life, which may not be represented by maternal residence at the time of the birth or neonatal residence at death. The mother may have lived far from the place she gave birth during part or all of the pregnancy. It may be less likely that the neonate who died was born and lived far from the place of death.
  • The data presented are based on the location of the residence at the time of birth or death.  The place of residence or potential exposure during gestation or at the time of conception when an exposure that may have affected the outcome could have occurred, may be different.

For additional information, please read the FAQ

Available Data on Reproductive Mortality

Click the Maps and Tables button on this page to access the following measures for reproductive mortality in your community. The most current available data will be shown. Be sure to check the site periodically as new data are added each year. To protect privacy, no information is shown that could identify an individual.

  • Average annual number and rate per 1,000 live births of perinatal (≥ 28 weeks gestation plus infants less than 7 days old) mortality by community, county, and statewide over 5 year period
  • Average annual number and rate 1,000 per live births of infant (<1 year of age) deaths by community, county, and statewide over 5 year period
  • Average annual number and rate per 1,000 live births of neonatal (<28 days of age) deaths by community, county, and statewide over 5 year period
  • Average annual number and rate per 1,000 live births of postneonatal (≥ 28 days to <1 year of age) deaths by community, county, and statewide over 5 year period

Premature Births

A premature birth occurs when an infant is born at least 3 weeks before the scheduled due date. Data for premature births are reported by the number and percentage of premature births (born before completing 37 weeks of gestation) and very premature births (born before completing 32 weeks of gestation).

Being born prematurely is the leading cause of death among infants. It is also a leading cause of infant illnesses, diseases, and long-term disabilities including:

Did You Know?
The percentage of premature births rose significantly in the United States and Massachusetts between 1990 and 2006 but has been declining since then; likely due to reduced use of "elective" procedures, such as induced labor and caesarian delivery.

Source: National Vital Statistics Report volume 61, number 1 2012
  • Mental retardation
  • Cerebral palsy
  • Breathing and respiratory problems (premature lung development)
  • Feeding and digestive problems (including birth defects such as gastroschisis)
  • Vision and hearing loss

Three groups of women are at greatest risk of premature birth:

  • Women who have had a previous premature birth
  • Women who are pregnant with twins, triplets, or more
  • Women with certain uterine or cervical abnormalities

Exposures during pregnancy to air pollution or lead and some solvents in drinking water have been related to an increase risk of giving birth to a baby prematurely. For a list of all known risk factors for premature birth, please click the FAQ link on the tool bar on the right.

 

Data Considerations

When reviewing and interpreting data on premature births, it is important to take into consideration the following:

  • The premature birth counts and percentages for EPHT are based on live singleton births only. Proportions of premature births among live multiple birth categories may also be informative measures, particularly since plural births are a risk factor, but are not considered in the EPHT measures.
  • There may be uncertainties associated with gestational age estimates due to imperfect maternal recall or misidentification of the last normal menstrual period due to post conception bleeding and/or delayed ovulation.
  • Increased premature birth counts and percentages do not necessarily mean that environmental exposures are the cause. Environmental exposures may be one of several reasons for a premature or low birth weight birth.
  • Premature birth counts and percentages may be affected by a number of factors. For example, when a fetus is terminated prior to 37 weeks gestation that otherwise could have resulted in a live birth, the rate of premature birth decreases. Conversely, when an induced termination does not occur, a premature birth may be gained and the percentage increases. Therefore, low premature birth counts and percentages could indicate high fetal mortality and poor reproductive health of a population or a high abortion rate, whereas high premature birth counts and percentages could be a result of advanced technology and life-saving techniques.
  • The data presented are based on the location of the residence at the time of birth or death.  The place of residence or potential exposure during gestation or at the time of conception, when an exposure that may have affected the outcome could have occurred, may be different.

For additional information, please read the FAQ

Available Data on Premature Births
Click the Maps and Tables button on this page to access the following measures for premature births in your community. The most current available data will be shown. Be sure to check the site periodically as new data are added each year. To protect privacy, no information is shown that could identify an individual.
  • Annual number and percent of premature (less than 37 complete weeks gestation) live singleton births by county and statewide
  • Average annual number and percent of very premature (less than 32 complete weeks gestation) live singleton births by county and statewide over 5 year period

Sex Ratio at Birth

Picture of 3 toddlers sitting and smiling

The sex ratio at birth is the ratio of male to female births. In 2011, the sex ratio at birth (male to female) in the United States was 1.05. Slightly more males were born than females.

Numerous studies have reported changes in the ratio of males to females at birth with a reduction in male relative to female births in different countries throughout the world. Although the mechanism which determines the sex of the infant is not completely understood, some studies have suggested that environmental hazards, particularly endocrine disruptors, can affect how many males are born.

Did You Know?

The Northeast region has the lowest sex ratio in the U.S.

Source: U.S. Census Bureau 2011

Other factors besides environmental exposures can affect the sex ratio. A reduced sex ratio at birth has been linked to older-aged parents and parental smoking and an increased sex ratio has been linked to premature births.

 

Data Considerations

When reviewing and interpreting sex-ratio at birth data, it is important to take into consideration the following:

  • Sex ratio does not consider the inability to become pregnant, which may potentially be caused by environmental exposures.
  • The data presented are based on the location of the residence at the time of birth.  The place of residence or potential exposure during gestation or at the time of conception, when an exposure that may have affected the outcome could have occurred, may be different.

For additional information, please read the FAQ

Available Data on Sex Ratio

Click the Maps and Tables button on this page to access the following measure for sex ratio in your community. The most current available data will be shown. Be sure to check the site periodically as new data are added each year. To protect privacy, no information is shown that could identify an individual.

  • Annual male to female sex ratio at birth (term, singleton live births only) by community, county, and statewide
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