Moderate and late preterm birth linked to later cardiometabolic disorders

Being born moderate to late preterm sets the stage for cardiometabolic disorders later in life, meaning such risks are not limited to early preterm. “There is growing awareness that late preterm newborns are not as physiologically or metabolically mature as term newborns and that late preterm birth may confer negative consequences across a child’s life course,” said researchers in a study published in JAMA Network Open. This may indicate a need for screening and early-life interventions for these children to help prevent cardiometabolic outcomes later in life, said study coauthor Laura Anderson, PhD, professor of public health at McMaster University. “While late preterm may have fewer overall risks than those born even earlier, they still have higher risks than those born at full term." Late preterm birth, defined as 34 to 36 weeks’ gestation, accounts for 75% of all preterm births. This proportion has been rising steadily since 1990. At the same time, contributing risk factors for spontaneous preterm delivery such as older maternal age, multiple-gestation births, maternal obesity and maternal diabetes, have also been increasing. But generally, the question of whether late preterm birth affects cardiometabolic risk (CMR) had not fully been answered. In children, “CMR is commonly defined as a continuous risk score based on the clustering of age- and sex-standardized central adiposity, high serum lipid levels, glucose levels, and blood pressure,” the study said. To address this gap, the researchers conducted a retrospective study to evaluate whether late preterm birth, gestational age as a continuous measure and size for gestational age, were associated with CMR among children aged three-to-12 years. They used data from the Applied Research Group for Kids (TARGet Kids!) primary care practice–based research network in Toronto—an open longitudinal cohort study, launched in 2008. Children who were younger than six years at enrollment were recruited from pediatric or family practice clinics in the greater Toronto area, are followed throughout childhood and undergo regular health visits. For this study, a total of 1,742 children who had CMR outcomes measured at ages three-to-12 years between April 1, 2006, and Sept. 30, 2019, were included. They had a mean age of, 5.6 years and just over half, 54% (951) were male. Of these, 87 children (5.0%) were born moderately preterm (less than 34 weeks gestation), 145 (8.3%) were born late preterm (34 to 36 weeks gestation), 455 (26.1%) were born early term (37 to 38 weeks gestation), and 1,055 (60.6%) were born full term (39 weeks gestation or more). When they were compared to children born full term, those who were born moderately preterm and late preterm had higher CMR scores. Each additional gestational week was associated with a slight decrease in CMR. Read: 'It saves lives': Medical study says established heart drug good for strokes, too Children born late preterm versus full term were more likely to be from families with lower annual income less than $50,000 (59.3% versus 53.6%); their mothers were more likely to be older (mean age of 34.2 years compared to 33.5 years) and of non-European ethnicity. They were also significantly more likely to have gestational diabetes, gestational hypertension, preeclampsia or eclampsia. Overall, late preterm birth children had a higher mean overall CMR than those born at term. Moderately preterm birth had a slightly higher mean overall CMR than late preterm. When gestational age was evaluated as a continuous variable, each additional gestational week was associated with slightly lower mean overall CMR. For individual CMR components, late preterm birth and moderately preterm birth was associated with higher systolic blood pressure (SBP) and lower HDL cholesterol levels than those who were born full-term birth. Only moderately preterm birth was associated with higher triglyceride levels than full-term birth. “There was no evidence of an association between early term birth and any of the individual CMR components,” the study said. Large gestational age was associated with higher waist circumference, whereas those who had small gestational age tended to have lower waist circumference. “These findings may have clinical implications because both late preterm birth and possibly large gestational size may be important risk factors for cardiometabolic disorders,” said Dr. Anderson. With CMR scores tracking from childhood into adulthood, early preventive evaluation and CMR monitoring starting early in childhood may be warranted for preterm-born children. “Screening could involve doctors routinely measuring cardiometabolic risk factors, such as lipids and blood pressure, in children born late preterm. Routine screening could allow for early intervention that may contribute to the prevention of later life cardiovascular disease,” she said. “This is fascinating and important work,” said Dr. Michael Khoury, scientific director of the Canadian Pediatric Cardiology Association, who was not part of the study. “We commonly emphasize that atherosclerosis and cardiovascular risk is a lifelong process beginning in early childhood. It has become increasingly more evident that the more accurate statement would be that cardiovascular risk begins in utero. This study further strengthens this notion,” he said. It is notable that the long-term ramifications of pre-term birth are not reserved only to those with extreme prematurity. Cardiovascular risk is a lifelong process and a priority is to prevent the development of modifiable cardiovascular risk factors and the occurrence of cardiovascular disease in young adulthood. “The best way to do that is to mindfully assess risk starting early in childhood,” he said. Read: QUIZ: Test your knowledge of cardiovascular complications in patients with diabetes Cardiovascular risk screening typically involves assessment of height, weight, BMI calculation, waist circumference and waist-to-height ratio. Blood pressure screening is important, too. “Screening lipid assessments starting at the age of two are also appropriate, more so to detect inherited lipid disorders such as familial hypercholesterolemia which are typically clinically silent,” he said.

Moderate and late preterm birth linked to later cardiometabolic disorders

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