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The timing hypothesis and body proportionality of the intra-uterine growth retarded infant

Lynnette Neufeld1, David L. Pelletier, Jere D. Haas

  • 1Division of Nutritional Sciences, Cornell University, Ithaca, New York.

American Journal of Human Biology : the Official Journal of the Human Biology Council
|September 5, 2001
PubMed

Insights

Prenatal stress timing does not determine infant growth patterns. Third trimester stress impacted birth weight and length, but not ponderal index, challenging existing hypotheses on intra-uterine growth retardation (IUGR).

Area of Science:

  • Human Biology
  • Maternal-Fetal Medicine
  • Developmental Pediatrics

Background:

  • Intra-uterine growth retardation (IUGR) is a complex condition with varying neonatal outcomes based on infant proportionality.
  • The etiology of disproportionate versus proportionate IUGR remains poorly understood.
  • The timing of prenatal stress during gestation is hypothesized to influence specific growth parameters.

Purpose of the Study:

  • To investigate the relationship between the timing of gestational stress and the type of IUGR (proportionate vs. disproportionate).
  • To test if second trimester stress affects linear growth and third trimester stress affects ponderal index.
  • To examine the impact of seasonal stress (pre-harvest rainy season) on fetal growth in a Malawian cohort.

Main Methods:

  • Prospective study of 755 full-term mother-infant pairs in rural northern Malawi.
  • Assessment of exposure to the pre-harvest rainy season (PHRS) during the second and third trimesters of gestation.
  • Measurement of infant birth weight, length, and ponderal index (weight/height^3) at term.

Main Results:

  • Second trimester PHRS exposure showed no association with birth weight, length, or ponderal index.
  • Third trimester PHRS exposure was associated with reduced birth weight and length.
  • Third trimester PHRS exposure did not significantly affect the ponderal index.

Conclusions:

  • The study's findings do not support the hypothesis that specific gestational trimester stress uniquely impacts linear growth or ponderal index in IUGR.
  • Prenatal stress, particularly in the third trimester, appears to affect overall fetal size (weight and length).
  • Linear growth may be more sensitive to or affected earlier by prenatal stress than ponderal index, suggesting a need to re-evaluate current IUGR timing hypotheses.

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