Inverse Relationship between Birth Weight and Blood Pressure in Growth-Retarded but Not in Appropriate for Gestational Age Infants during the First Week of Life

Abstract

Background: Various studies have shown an association between low birth weight and the prevalence of elevated blood pressure later in life. However, a relationship between birth weight and blood pressure in the neonatal period has not been investigated yet. Objective: To study the relationship between birth weight and blood pressure during the first week of life. Methods: Systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MBP) were measured every 8 h during days 1, 2, 3, 4 and 7 in 44 small for gestational age (SGA) infants and compared with those of infants born with a birth weight appropriate for gestational age (AGA). The infants were matched for gestational age and gender. Results: Meanbirth weight (range) in the SGA group was 778 (460–1,400) g versus 1,524 (960–2,730) g in the AGA group, and mean (range) gestational age of both groups was 30.5 (27.3–35.5) weeks. In the first week of life, SGA and AGA infants had similar SBP, DBP and MBP. Also, after adjustment for confounders (maternal medication, smoking), SBP, DBP and MBP rose equally in SGA and AGA infants during the first week of life. AGA infants showed a positive correlation between birth weight and blood pressure, but SGA infants showed an inverse correlation. Conclusions: Although differences in blood pressure were found between SGA and AGA infants in the first week of life, the inverse relationship between birth weight and blood pressure in SGA infants warrants follow-up studies to investigate a possible link with late cardiovascular disease.