There are over 68,000 babies born to Massachusetts residents each year. Environmental factors where we live, work, and play can influence reproductive health. Contaminants in the air, water, and everyday items may also influence birth outcomes. These factors, combined with age, genetics, and maternal health, can all play a role in having a healthy baby. Poor reproductive and birth outcomes include infertility, premature birth, low birthweight, and fetal and infant deaths. Birth defects are also tracked through the Environmental Public Health Tracking Program.
What Are Reproductive And Birth Outcomes?
Reproductive and birth outcomes cover a range of health measures relating to the ability to conceive, carry, and deliver a healthy, full-term baby that remains throughout the first year of life.
The Massachusetts Environmental Public Health Tracking Program (MA EPHT) uses the following measures to track reproductive and birth outcomes:
Sex ratio:
The sex ratio is the ratio of male births per 1,000 female births.
Numerous studies have reported 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.
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. An increased sex ratio has been linked to premature births.
Preterm (premature) birth:
Preterm birth occurs when a baby is born before the 37th week of pregnancy. A baby is considered a very preterm birth when it is born before the 32nd week of pregnancy.
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. Exposures during pregnancy to air pollution or lead and some solvents in drinking water have been related to an increased risk of giving birth to a baby prematurely.
Other risk factors include, but are not limited to:
- Carrying multiple fetuses (twins, triplets, or more) or having previous premature births
- Health problems during pregnancy, such as high blood pressure, diabetes, infections, and clotting disorders or problems with the uterus or cervix
- Cigarette smoking or exposure to second-hand smoke, alcohol use, or illicit drug use during pregnancy
- Age at pregnancy that is younger than 17 years old or older than 35 years.
- Late or no prenatal care
- Social and economic factors, such as domestic violence, lack of social support, low income, racism, or stress. Babies born to parents that identify as Black, Hispanic, and Indigenous or Other are more likely to be born preterm.
- Long working hours or long periods of standing during pregnancy.
- Being underweight or overweight before pregnancy
- Time between births, less than 6-9 months between birth and the beginning of the next pregnancy.
Low birthweight:
Low birthweight (among full-term births) is when a baby is born at a low weight (less than 5.5 pounds). We track low birthweight among singleton, full-term births because babies born too early or as part of a multiple birth are often low weight. This measure is also called small for gestational age.
Very low birthweight (regardless of gestational age) is when a baby is born at a very low weight (less than 3.3 pounds). We track very low birthweight among singleton births regardless of gestational age.
Low birthweight occurs when the growth of the fetus is abnormally slow. Compared to normal birthweight infants, low birthweight infants may be more at risk for:
- Illness within 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 birthweight infants. Other factors associated with low birthweight include non-environmental risk factors, such as exposure to cigarette smoking (from mothers who smoke or from second-hand smoke) and no or late prenatal care.
Infant mortality:
Infant mortality is when a baby dies before their first birthday. We track perinatal (28 weeks gestation to 7 days of age), neonatal (less than 28 days of age), post-neonatal (28 days of age to 1 year of age), and infant (less than 1 year of age) mortality.
Identifying populations with higher perinatal, neonatal, and post-neonatal 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. Risk factors for mortality include:
- Smoking
- Substance abuse
- Poor nutrition
- Lack of prenatal care
- Medical problems, such as anemia or nutritional deficiency, diabetes, hypertension, and infection during pregnancy
- Chronic illness
- Sudden infant death syndrome (SIDS)
- Complications of pregnancy such as cord prolapse, placenta previa, and placenta abruption
- Air pollution (particulate matter)
Total Fertility Rate:
Fertility refers to the ability to have live children and is measured by the total fertility rate. This rate is an estimate of the number of births that a group of 1,000 birthing people would have over their lifetimes. 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 infertility in women and people who can give birth include:
- Age
- Smoking
- 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).
Additionally, lifestyle, overall health, and environmental factors can affect the number and quality of sperm. 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.
Why Is MA EPHT Tracking Reproductive and Birth Outcomes?
Tracking these measures helps us understand the connection between reproductive and birth outcomes and the environment. MA EPHT provides statewide, county, community, and census tract level data about reproductive and birth outcomes that can be linked to environmental exposure and hazard data nationally and within the state. We study the trends and patterns in these data across time, geography, and demographics. This helps us better understand how the environment influences our health and identify populations at risk for, or suffering from, poor health outcomes.
For example, low birthweight is tracked as one of 4 health criteria to identify Vulnerable Health Environmental Justice Populations in Massachusetts. Environmental Justice Populations are segments of the population that have higher-than-average rates of environmentally related health outcomes. These populations also have higher percentages of minorities, people experiencing language isolation, and people living with low income. 1
Due to increased environmental exposures and differences in prenatal care, as well as other factors, people of color in MA are more likely to experience issues in pregnancy, preterm births, and infant and maternal mortality. 2
For more information, check out:
1 Environmental Justice Populations in Massachusetts
2 PHIT Health Equity Data Stories on Reproductive and Birth Outcomes
What Environmental Exposures Affect Reproductive And Birth Outcomes?
Exposure does not necessarily mean you or your baby will be harmed. However, environmental toxins may be especially dangerous to babies while they are growing in the womb. Exposure to high levels of the following could impact you or your baby’s health:
- Smoking and secondhand smoke from cigarettes is associated with premature birth, low birthweight, and possibly fetal death or miscarriage.
- Air pollution from car exhaust and industrial sources is associated with low birthweight and premature birth.
- Lead is often found in old homes. It can cause premature birth, low birthweight, spontaneous fetal death, or miscarriage.
- Mercury, mostly found in large fish, can harm an unborn baby’s nervous system.
- Pesticides used in large amounts, such as in farming and agricultural areas, are associated with miscarriage, premature birth, low birthweight, and other health problems.
- Endocrine-Disrupting Chemicals, like BPA, PCBs, and phthalates, may impact fertility and child development. They can be found in many household products, such as make-up, plastic containers, and the lining of canned foods.
How Can I Reduce My Risk?
A safe environment is just one part of a healthy pregnancy. Medical conditions, social and economic factors, and human behavior can all impact health outcomes.
To reduce your risk of poor reproductive and birth outcomes…
Talk to Your Healthcare Provider
- See a healthcare provider before you get pregnant to discuss any health risks, including over-the-counter and prescription medications that are safe or unsafe to take during pregnancy and to become up-to-date on vaccinations.
- Start prenatal care as soon as possible.
- Talk to your healthcare provider about ways to prevent infections and seek help when you are sick.
- If you work with any chemicals, ask how they may impact your pregnancy.
Try to Improve Your Health
- Talk to your healthcare provider about maintaining a healthy weight.
- Take a vitamin with 400 micrograms (mcg) of folic acid every day.
- Treat any existing conditions you may have, such as diabetes.
- Use birth control or condoms if you do not want to get pregnant.
Avoid Harmful Substances
- Avoid cigarettes, including e-cigarettes/vapes, and secondhand smoke. Contact the Massachusetts Tobacco Cessation and Prevention Program (MTCP) if you need help quitting tobacco.
- Do not use alcohol, marijuana, or illegal drugs.
- Seek professional help if you are managing addiction while pregnant.
Prevent Environmental Exposures
- If possible, avoid using fireplaces and wood-burning stoves.
- Do not handle chemicals or go to places where chemicals are sprayed.
- Try to avoid pollution from traffic.
- Avoid mosquitoes.
- Stay away from wild or pet rodents, live poultry, lizards and turtles, and do not clean cat litter boxes while pregnant.
- Wash your hands before and after preparing food, after touching pets and animals, and after changing diapers or wiping runny noses. Do not put a young child’s food, utensils or pacifiers in your mouth.
- Follow fish consumption guidelines to avoid exposure to mercury or other contaminants.
- Have your home tested for lead if it was built before 1978. You can find more information on lead from the Massachusetts Childhood Lead Poisoning Prevention Program.