10.9: Infant Health

Preterm birth and low birth weight

One key measure of infant health is to increase the proportion of babies born at full term. For public health, at the population level, this is a high priority. A related measure that we use to monitor the health of babies in a population -- as well as to clinically monitor the health of a specific baby -- is weight at birth.

Preterm births are defined as those prior to 37 weeks gestation. The rate of preterm births in the US rose from 9.6% in 2014 to 10.4% in 2024 (March of Dimes, 2026).  Babies born premature are more likely to have a range of health problems, including having their organs not completely developed and having developmental delays.

About half of pre-term births have no clear cause. However, we can identify risk factors associated with higher rates of pre term births, such as past health history of the mother, tobacco and alcohol use, exposure to domestic violence, drug use, lack of social support, some infections, some chronic conditions, air pollution, lack of prenatal care, and being either younger than 17 or older than 35 years of age. Multiple births (twins, triplets, etc.) are also more likely to occur preterm, compared with singleton birth (one baby).

Low birth weight (LBW) is a term that refers to babies born weighing less than 2500 grams (about 5 lb. 8 oz.). A very low birth weight (VLBW) baby is one born weighing less than 1500 grams, or about 3 lbs. 5 oz.). Unfortunately, this is not a rare event. According to the March of Dimes, in 2024, 1 in 12 babies (8.5% of live births) was low birthweight (LBW) in the United States.

There is considerable overlap between preterm births and LBW -- but some full term babies are still born with LBW.

Babies born preterm and/or with LBW are at higher rate of disability and death, along with difficulties with breathing, vision, and hearing (CDC, 2024).

The risk factors for having a baby with LBW are largely similar to those described above for preterm birth.  These include behavioral risk factors like a pregnant person's diet, degree of weight gain, alcohol use, tobacco use, and timing of prenatal care. Public health programs can reduce these risks by improving access to care, patient education, nutrition support programs, smoking cessation, etc. Often, public policy can reduce risk factors across the population; for example, WIC and TANF programs expand access to healthy food, and the Affordable Care Act requires prenatal care be provided without a copay.

Other risk factors -- like the long term stresses of economic insecurity or exposure to racism (the social determinants of health discussed in an earlier chapter) -- are harder to change through behavioral interventions, yet they can be addressed through public policy and through community actions.  A policy example: California requires maternal health providers to receive training to reduce implicit bias. A community example: the Abundant Birth Project attempts to reduce stress for Black and Pacific Islander birthing parents who are at increased risk by providing economic support during and after pregnancy. 

Alcohol, Tobacco and Other Drugs during Pregnancy

Tobacco use during pregnancy is the leading modifiable risk factor for low birth weight and other poor birth outcomes. Exposure to second-hand smoke is also a risk to a growing fetus. 

Alcohol and other drugs also contribute to poor birth outcomes and poor infant health. One of the most serious complications among newborns is fetal alcohol syndrome, which is on the more extreme end of a broader category of fetal alcohol spectrum disorders (FASD) (Mayo Clinic, 2024). Fetal alcohol syndrome refers to a group of abnormalities that may include growth retardation, abnormal appearance of face and head, and deficits of central nervous system function, including mental retardation, in babies born to mothers who have consumed heavy amounts of alcohol during their pregnancies. Babies born with any significant exposure to alcohol may experience effects including lower birth weight, learning difficulties, behavioral issues, and slower physical development. 

Breastfeeding

Breastfeeding is a vital component of infant health. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for first six months of life and continuing breastfeeding for two years or longer, as long as there is no medical reason not to (e.g., some condition or illness in the birthing parent or infant that makes breastfeeding impossible). 

From the AAP policy on breastfeeding: "Breastfeeding and human milk are the normative standards for infant feeding and nutrition. The short- and long-term medical and neurodevelopmental advantages of breastfeeding make breastfeeding, or the provision of human milk, a public health imperative. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for approximately 6 months after birth. Furthermore, the AAP supports continued breastfeeding, along with appropriate complementary foods introduced at about 6 months, as long as mutually desired by mother and child for 2 years or beyond" (Meek & Noble, 2022, paragraph 1).

Breastfeeding supports the baby's immune function, and it is associated with a lower rate of chronic diseases later in life. It is also associated with decreased risk of obesity later in life.

Hospital policies can do a lot to support (or discourage) breastfeeding. The Baby-Friendly Hospital movement has supported hospital policies like rooming babies with their birthing parents, providing no other food than breast milk unless medically indicated, helping mothers or birthing parents initiate breastfeeding within an hour of birth, and other measures that make it more likely that the birthing parent will be able to breast feed her or their child. Doulas, midwives, and breastfeeding educators like those in La Leche League also can support a new parent with breastfeeding -- while breastfeeding is natural, it is not always easy! 

Workplace policies also play a role. Can a birthing parent pump breast milk privately at work? Are breaks for breastfeeding provided? What about maternity leave or other paid family leave?

Sudden Infant Death Syndrome (SIDS)

SIDS refers to the sudden unanticipated death of an infant in whom, after examination, there is no recognized cause of death. It is a very tragic occurrence! It is also to some extent preventable. The national public health campaign, Safe to Sleep, taught parents to put babies to sleep on their backs, instead of their fronts or sides, and to reduce clutter in the crib (toys, blankets, etc.). This campaign had a stunning success rate -- rates of SIDS dropped by 30% in the first few years, and then reached and sustained a reduction of over 50% of death for many years.  An uptick in SIDS deaths of 12% in 2020 and 2021 during the covid-19 pandemic may have resulted from less access to pediatric care and community programs during that time, and therefore some parents did not have the Safe to Sleep information needed. Rates of SIDS deaths declined again in 2023 and 2024. However, in 2025, the Trump Administration terminated this highly successful program -- the Safe to Sleep website is still up, but the program is no longer staffed, according to STATnews and NPR. 

References

Belkoura, IM. (2025, April 30). NIH cancels participation in Safe to Sleep campaign that decreased infant deaths. STATnews. https://www.statnews.com/2025/04/30/...infant-deaths/

California Preterm Birth Initiative. (n.d.) Abundant Birth Project. https://pretermbirthca.ucsf.edu/cont...-birth-project

Centers for Disease Control and Prevention (CDC). (2024). Preterm birth. https://www.cdc.gov/maternal-infant-...rth/index.html

Godoy, M. (2025, May 5). Trump cuts baby 'Safe to Sleep' team. NPR. https://www.npr.org/2025/05/05/nx-s1...leep-sids-baby

March of Dimes. (2026). Preterm birth. https://www.marchofdimes.org/peristats/data

March of Dimes. (2026). Data summary for the United States. https://www.marchofdimes.org/perista.../united-states 

Mayo Clinic. (2024). Fetal alcohol syndrome. https://www.mayoclinic.org/diseases-...s/syc-20352901

Meek, JY, Noble, L. (2022, July). Section on  Breastfeeding; Policy Statement: Breastfeeding and the Use of Human Milk. Pediatrics; 150 (1): e2022057988. 10.1542/peds.2022-057988

Seabert, D., McKenzie, J. F., Pinger, R. R. (2025). McKenzie's An Introduction to Community & Public Health. United Kingdom: Jones & Bartlett Learning.