Red blood cell parameters in early childhood: a prospective cohort study.

OBJECTIVES: Red blood cell parameters are frequently used biomarkers when assessing clinical status in newborns and in early childhood. Cell counts, amounts, and concentrations of these parameters change through gestation and after birth. Robust age-specific reference intervals are needed to optimize clinical decision making. METHODS: The Copenhagen Baby Heart Study (CBHS) and the COMPARE study are prospective cohort studies including red blood cell parameters from 7,938 umbilical cord blood samples and 295 parallel venous blood samples from newborns with follow-up at two and at 14-16 months after birth. RESULTS: For venous blood at birth, reference intervals for hemoglobin, erythrocytes, and hematocrit were 145-224 g/L, 4.1-6.4 × 1012/L, and 0.44-0.64, respectively. Hemoglobin, erythrocytes, and hematocrit were lower at birth in children delivered by prelabor cesarean section compared to vaginal delivery. Conversion algorithms based on term newborns were: venous hemoglobin=(umbilical cord hemoglobin-86.4)/0.39; venous erythrocytes=(umbilical cord erythrocytes-2.20)/0.44; and venous hematocrit=(umbilical cord hematocrit-0.24)/0.45. CONCLUSIONS: This study presents new reference intervals for red blood cell parameters in early childhood, describes the impact of delivery mode, and provide exact functions for converting umbilical cord to venous blood measurements for term newborns. These findings may improve clinical decision making within neonatology and infancy and enhance our clinical understanding of red blood cell parameters for health and diseases in early life.

Coagulation parameters in the newborn and infant - the Copenhagen Baby Heart and COMPARE studies.

OBJECTIVES: The coagulation system is not fully developed at birth and matures during the first months of infancy, complicating clinical decision making within hemostasis. This study evaluates coagulation parameters at birth and two months after birth, and tests whether cord blood can be used as a proxy for neonatal venous blood measurements. METHODS: The Copenhagen Baby Heart Study (CBHS) and the COMPARE study comprise 13,237 cord blood samples and 444 parallel neonatal venous blood samples, with a two month follow-up in 362 children. RESULTS: Because coagulation parameters differed according to gestational age (GA), all analyses were stratified by GA. For neonatal venous blood, reference intervals for activated partial thromboplastin time (APTT) and prothrombin time (PT) were 28-43 s and 33-61% for GA 37-39 and 24-38 s and 30-65% for GA 40-42. Reference intervals for international normalized ratio (INR) and thrombocyte count were 1.1-1.7 and 194-409 × 109/L for GA 37-39 and 1.2-1.8 and 188-433 × 109/L for GA 40-42. Correlation coefficients between umbilical cord and neonatal venous blood for APTT, PT, INR, and thrombocyte count were 0.68, 0.72, 0.69, and 0.77 respectively, and the distributions of the parameters did not differ between the two types of blood (all p-values>0.05). CONCLUSIONS: This study describes new GA dependent reference intervals for common coagulation parameters in newborns and suggests that cord blood may serve as a proxy for neonatal venous blood for these traits. Such data will likely improve clinical decision making within hemostasis among newborn and infant children.

Lipoprotein(a) Levels at Birth and in Early Childhood: The COMPARE Study.

BACKGROUND AND OBJECTIVE: High lipoprotein(a) is a genetically determined causal risk factor for cardiovascular disease, and 20% of the adult population has high levels (ie, >42 mg/dL, >88 nmol/L). We investigated whether early life lipoprotein(a) levels measured in cord blood may serve as a proxy for neonatal venous blood levels, whether lipoprotein(a) birth levels (ie, cord or venous) predict levels later in life, and whether early life and parental levels correlate. METHODS: The Compare study is a prospective cohort study of newborns (N = 450) from Copenhagen, Denmark, including blood sampling of parents. Plasma lipoprotein(a) was measured in cord blood (N = 402), neonatal venous blood (N = 356), and at 2 (N = 320) and 15 months follow-up (N = 148) of infants, and in parents (N = 705). RESULTS: Mean lipoprotein(a) levels were 2.2 (95% CI, 1.9-2.5), 2.4 (2.0-2.7), 4.1 (3.4-4.9), and 14.6 (11.4-17.9) mg/dL in cord, neonatal venous, and 2- and 15-month venous samples, respectively. Lipoprotein(a) levels in cord blood correlated strongly with neonatal venous blood levels (R2 = 0.95, P < 0.001) and neonatal levels correlated moderately with 2- and 15-month levels (R2 = 0.68 and 0.67, both P < 0.001). Birth levels ≥ 90th percentile predicted lipoprotein(a) > 42 mg/dL at 15 months with positive predictive values of 89% and 85% for neonatal venous and cord blood. Neonatal and infant levels correlated weakly with parental levels, most pronounced at 15 months (R2 = 0.22, P < 0.001). CONCLUSIONS: Lipoprotein(a) levels are low in early life, cord blood may serve as a proxy for neonatal venous blood, and birth levels ≥ 90th percentile can identify newborns at risk of developing high levels.