From the Guidelines
Being born at 38 weeks versus 40 weeks is unlikely to significantly affect adult height. Gestational age at birth within the full-term range (37-42 weeks) has minimal impact on ultimate adult height compared to other factors like genetics, nutrition, and overall health during childhood and adolescence. While the provided study 1 discusses the risks associated with pre-term birth, it defines pre-term birth as delivery prior to 37 weeks gestation, which does not directly apply to births at 38 or 40 weeks. Key factors influencing adult height include:
- Genetic factors, accounting for approximately 80% of height variation
- Adequate nutrition throughout childhood
- Proper hormone function, especially growth hormone and thyroid hormone
- Absence of chronic diseases that might impair growth Babies born at 38 weeks may be slightly smaller at birth than those born at 40 weeks, but this initial difference typically disappears during early childhood as growth trajectories normalize. Parents concerned about their child's growth should focus on providing proper nutrition, regular healthcare, and monitoring growth patterns during childhood rather than worrying about whether birth occurred at 38 or 40 weeks gestation. It's also important to note that the study 1 highlights the increased risk of cardiovascular disease associated with pre-term birth, but this is more relevant to births prior to 37 weeks gestation.
From the Research
Effect of Gestational Age on Adult Height
- Being born at 38 weeks versus 40 weeks may have an impact on adult height, according to a study published in 2005 2.
- The study found that birth length is a stronger predictor of adult height than birth weight, and that the effects of birth length on adult height are stronger among those born at gestational age 39 to 41 weeks.
- However, the study also found that the effects of birth length on adult height are less pronounced among preterm births (less than 37 weeks) compared to term births.
Comparison of Gestational Ages
- A study published in 2016 3 found that children born at 38 weeks had a slightly higher risk of developmental vulnerability compared to those born at 39 or 40 weeks.
- However, the study did not specifically examine the relationship between gestational age and adult height.
- Another study published in 2005 2 found that the strongest associations between birth length and adult height were seen among those born at gestational age 39 to 41 weeks.
Preterm Birth and Adult Height
- Preterm birth is defined as birth before 37 completed weeks of pregnancy 4, 5, 6.
- While preterm birth has been linked to various health problems, the relationship between preterm birth and adult height is not well established.
- A study published in 2005 2 found that the effects of birth length on adult height are less pronounced among preterm births compared to term births, but did not examine the relationship between preterm birth and adult height specifically.