Low birth-weight babies:

Colorado experiencing higher rate than national average

The rate of low birth-weight babies born in Colorado has been higher than the national average since 1993, presenting higher risks for developmental issues ranging from cardiovascular diseases to infant mortality. While much is still unknown about low birth-weight babies, Colorado’s higher altitude may be the primary cause, with prenatal care as a primary solution. 


A low birthweight baby is defined as an infant weighing less than 5 pounds, 8 ounces at birth. Birthweight is commonly thought to be an indicator of the health of a child. When a smaller child is born, there is increased concern about whether or not the placenta of the mother was delivering necessary nutrients to the fetus. The consequences of such can be significant.


“If a baby is small because of a mom’s small placental disease… there is an increased risk of stillbirth,” said Anna Euser, an assistant professor of maternal fetal medicine at the University of Colorado.


While infant mortality is a concern, it is not common in Colorado, said Mary Faltynski. Faltynski is a registered nurse and the program coordinator for the GENESIS Program of Boulder County, which offers services to teen mothers. Her concern is more so on the ability of the baby to latch on to the mother and breastfeed, which is very important for a child’s health.


“These babies often have trouble feeding,” said Faltynski. “They’re much more likely to spend more time in the NICU [Neonatal Intensive Care Unit].”


Low birth-weight babies being at a higher risk of not receiving proper nutrients during pregnancy and difficulty in breastfeeding can lead to future developmental issues, such as cardiovascular diseases, diabetes and pulmonary vascular diseases.


For mothers, Euser said the consequences are typically not physical, but rather “psychologically difficult.”


“A lot of moms blame themselves,” said Euser.


Euser said that as long as the baby is able to gain weight and control its temperature, there is not an immediate risk to its health. However, it is difficult to collect data on the long-term impact a low birth-weight has on a baby’s future. As a result, a lot is left unknown as to how critical low birth-weight is in the development of a healthy adult.


The cause for low birth-weight babies is often linked to premature babies, meaning the baby is born before 37 weeks of pregnancy. Full-term pregnancies typically last 39 to 40 weeks.


However, the rate of premature babies in Colorado is not higher than the national average, like low birth-weight babies are. For low birth-weight babies, Colorado has a higher rate of 9.0 percent as of 2017, while the U.S. has a rate of 8.1 percent, according to the United Health Foundation. For premature babies, Colorado has a lower rate of 8.7 percent as of 2018, while the U.S. rate is 9.6 percent.


The reason for this higher rate of low birth-weight babies, and not premature babies, is most likely because of the higher altitude of Colorado, said Colleen Julian, an assistant professor in the department of medicine at the University of Colorado. Julian studies hypoxia, otherwise known as limited oxygen availability, in various contexts such as fetal growth.


Through Julian’s research, she found that blood flow to a pregnant woman’s uterus, otherwise known as uterine artery blood flow, is reduced among women living in high altitude. Normally, said Julian, a pregnant woman’s uterine artery blood flow increases dramatically. This lack of blood flow to the uterus results in restricted growth, and thus, lower birth weights.


The exception to this, however, is found among women in Bolivia whose ancestors are a population of Andes people, said Julian. Despite being at a higher elevation in Bolivia, these women are protected from this reduced uterine artery blood flow and are associated with higher birth weight. Women who had only lived in Bolivia for a few generations, however, did not experience such protection and had more low birth-weight babies.


This suggests that the protection some women in Bolivia experienced is evidence of natural selection and is an adaptive feature that women may only develop after living many generations in high altitude, said Julian. In general, women inhabiting Colorado have not lived here long enough to develop such protection.


Moving forward, Julian is looking to do functional studies on prescription drugs like metformin, which is commonly used to treat diabetes, to test if they are effective in protecting pregnant women living in high altitude locations from this reduced artery uterine blood flow. This can be done by dilating, or widening, blood vessels and manipulating pathways in order to increase the blood flow.


“…It has the potential to be something that could be a clinically important finding,” said Julian.


However, the testing process on the effectiveness of such prescription drugs will take time. In the meantime, pregnant mothers concerned about having a low birth-weight baby can take preventative steps like avoiding drug use or smoking, which are commonly correlated to low birth-weight babies, and getting prenatal care.


Prenatal care is often regarded as one of the most important steps because of the services it offers to mothers, including being able to predict the size of a fetus prior to its birth. Julie Javernick, a certified nurse midwife, said that during prenatal care visits, doctors will monitor the fundal height of the uterus, which is the length from the pubic bone to the top of the uterus. This fundal height should correspond to the fetus’ gestational age, otherwise known as how far along the pregnancy is in weeks.


If the fundal height falls short, a specific ultrasound will be run to look at parameters such as blood flow and aging of the placenta to help determine if the baby is actually small for its age and needs to be induced earlier than thought. The reason for inducement, explained Javernick, is that blood flow decreases as the placenta ages, therefore, babies can actually lose weight if not removed from the uterus.


The importance of accessing prenatal care can be found within the GENESIS Program of Boulder County that serves teenage mothers, one of the most at-risk populations for having a low birth-weight baby. Despite this increased risk of having low birth-weight babies, Mary Faltynski said she has not seen higher rates in the program.


“We do have some extremely high-risk clients,” said Faltynski. “We’re pretty lucky that we actually have a very low, low birth-weight rate.”


The reason for this lower rate despite servicing a more at-risk population is most likely due to the program’s emphasis on prenatal care, said Faltynski.


“We do think that access to prenatal care impacts birthweight,” said Faltynski. “For the teens that we are able to connect with, because we make sure that they get prenatal care… that makes a difference.”


There is still much to be learned about the causes, impact and potential solutions for the higher rate of low birth-weight babies in Colorado. The issue is complex. However, action can still be taken to monitor pregnancy and help ensure a healthy baby.  


“I think it’s a combination of factors and there’s not a quick fix,” said Javernick, referring to the causes of low birth-weights. “I think the key is getting good, consistent prenatal care.”