Placental Growth Measures in Relation to Birth Weight in a Latin American Population

Grandi, Carlos; Veiga, Angélica; Mazzitelli, Nancy; Cavalli, Ricardo de Carvalho; Cardoso, Viviane

doi:10.1055/s-0036-1586721

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Revista Brasileira de Ginecologia e Obstetrícia

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Original Articles • Rev. Bras. Ginecol. Obstet. 38 (08) • Aug 2016 • https://doi.org/10.1055/s-0036-1586721 copy

Placental Growth Measures in Relation to Birth Weight in a Latin American Population

Medidas de crescimento placentário em relação ao peso de nascimento em uma população latino-americana

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Introduction

The placenta, translates how the fetus experiences the maternal environment and is a principal influence on birth weight (BW).

Objective

To explore the relationship between placental growth measures (PGMs) and BW in a public maternity hospital.

Methods

Observational retrospective study of 870 singleton live born infants at Hospital Maternidad Sardá, Universidad de Buenos Aires, Argentina, between January 2011 and August 2012 with complete data of PGMs. Details of history, clinical and obstetrical maternal data, labor and delivery and neonatal outcome data, including placental measures derived from the records, were evaluated. The following manual measurements of the placenta according to standard methods were performed: placental weight (PW, g), larger and smaller diameters (cm), eccentricity, width (cm), shape, area (cm2), BW/PW ratio (BPR) and PW/BW ratio (PBR), and efficiency. Associations between BW and PGMs were examined using multiple linear regression.

Results

Birth weight was correlated with placental weight (R2 =0.49, p < 0.001), whereas gestational age was moderately correlated with placental weight (R2 =0.64, p < 0.001). By gestational age, there was a positive trend for PW and BPR, but an inverse relationship with PBR (p < 0.001). Placental weight alone accounted for 49% of birth weight variability (p < 0,001), whereas all PGMs accounted for 52% (p < 0,001). Combined, PGMs, maternal characteristics (parity, pre-eclampsia, tobacco use), gestational age and gender explained 77.8% of BW variations (p < 0,001). Among preterm births, 59% of BW variances were accounted for by PGMs, compared with 44% at term. All placental measures except BPR were consistently higher in females than in males, which was also not significant. Indices of placental efficiency showed weakly clinical relevance.

Conclusions

Reliable measures of placental growth estimate 53.6% of BW variances and project this outcome to a greater degree in preterm births than at term. These findings would contribute to the understanding of the maternal-placental programming of chronic diseases.

Keywords:
Placenta; placental weight; placental characteristics; birth weight; gestational age

Characteristic	n^a	Mean	SD	Range
Weight (g)	870	432	120	110–838
Gestational age (w):
22–28	55	266	81.9^**
29–32	76	350	90.5
33–36	319	428	101.4
37–42	420	474	115.6
Weight z score^b	870	−1.1	0.9	−5.0–2.1
Term neonates	420	−1.4	0.9	−5.0–1.3^*
Preterm neonates	450	−0.9	0.8	−4.3–2.1^*
Largest diameter of placenta (cm)	862	16.6	2.5	5.0–29.0
Smallest diameter of placenta (cm)	862	12.4	2.9	3.0–23.0
Chorionic plate eccentricity^c	862	1.4	0.4	0.8–5.6
Disc thickness (cm)	820	3.0	0.6	1.0–7.0
Chorionic plate area (cm²)	862	164.8	55.8	15.7–397
Placental shape	870	4.1	2.6	−2–18
Oval (≥ 3 cm): 612/870 (70.4%)
Round (< 3): 258/870 (29.6%)
BPR	870	5.9	1.5	2.1–23.5
Term neonates	420	6.6	1.4	2.2–23.5^*
Preterm neonates	450	5.4	1.3	2.1–10.8^*
Gestational age (w):
22–28	55	3.7	1.0^**
29–32	76	4.8	0.9
33–36	319	5.8	1.1
37–42	420	6.6	1.5
PBR	870	17.6	5.1	4.2 - 46.0
Term neonates	420	15.5	3.5	4.1–44.6^*
Preterm neonates	450	19.5	5.6	9.1–46.0^*
Gestational age (w):
22–28	55	28.4	6.8^**
29–32	76	21.5	4.3
33–36	319	17.5	3.7
37–42	420	15.5	3.5
Efficiency 1^d	866	176.8	50.4	42.5–460
Efficiency 2^d	855	7.1	2.9	1.4–31.5
Efficiency 3^d	815	1.3	0.6	0.4–6.4

	Unadjusted models		Multivariate models^#
	Point estimate (95%CI)	R-squared	Model 1^a		Full Model^b
			Point estimate (95%CI)	Adjusted R-squared	Point estimate (95%CI)	Adjusted R-squared
Placental weight (g)	4.5 (4.2–4.8)	0.49^***	3.8 (3.4–4.3)^***	0.52^***	2.4 (2.1– 2.7)^***	0.78^***
Largest diameter (cm)	142.4 (1237–161.1)	0.21^***	23.3 (3.4–43.2)^**		16.4 (2.7– 30.9)^**
Smallest diameter (cm)	115.8 (99.0–132.6)	0.18^***	27.8 (11.6–44.1)^***		5.1 (−6.0–16.3)
Disc width (cm)	299.1 (210.7–387.5)	0.05^***	61.3 (−7.9–130.5)		17.1 (−30.7–65.1)

Measure	Gestational age
	≤ 32 w (n = 131)		33–36 w (n = 319)		37–42 w (n = 420)
	Point estimate (95%CI)	Adjusted R-squared^*	Point estimate (95%CI)	Adjusted R-squared^*	(95%CI)	Adjusted R-squared^*
Placental weight (g)	2.20 (1.59–2.82)	0.84^**	(1.72–2.62)	0.53^**	2.65 (2.62–3.04)	0.49^**
Large diameter (cm)	−17.90 (−39.14–3.32)		14.7 (−3.25–32.69)		15.27 (−4.52–35.06)
Small diameter (cm)	19.55 (1.92–37.17)		5.85 (−9.74–21.46)		8.32 (−8.23–24.88)
Disk width (cm)	−36.25 (−103.7–31.2)		−14.31 (−50.83–22.20)		−4.90 (−40.67–30.85)

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[1] Address for correspondence Carlos Grandi, PhD, Department of Pediatrics, Hospital Maternidad Sardá, Luca 2151, Buenos Aires, Argentina (e-mail: cgrandi@intramed.net).