Validation of modified World Health Organization classification for pregnant women with heart disease in a tertiary care center in southern Thailand

Figures & data

Table 1 Maternal characteristics and obstetric outcomes

Characteristics	Modified WHO classification				p-value
	Class I (N=48)	Class II (N=173)	Class III (N=32)	Class IV (N=78)
Age (years), mean (SD)	28.7 (5.8)	28.1 (6.5)	28.4 (5.7)	28.8 (6.8)	0.86
Nulliparity	56.2%	50.3%	37.5%	55.1%	0.33
Type of heart disease					<0.001
– Congenital	87.5%	46.8%	6.2%	41%
– Acquired	12.5%	53.2%	93.8%	59%
Surgical correction before pregnancy	56.2%	25.4%	65.6%	20.5%	<0.001
Referred cases	33.3%	39.9%	50.0%	71.8%	<0.001
Number of antenatal care visits, mean (SD)	10.5 (3.6)	10.3 (3.7)	9.3 (3.4)	8.1 (3.6)	<0.001
Gestational age at first antenatal care (weeks), mean (SD)	12.5 (6.0)	13.1 (6.5)	12.7 (6.5)	14.7 (6.8)	0.19
Gestational age at delivery (weeks), mean (SD)	37.8 (2.4)	37.8 (1.9)	36.6 (2.5)	36.0 (2.7)	<0.001
Mode of delivery					0.38
– Spontaneous vaginal delivery	33.3%	28.9%	34.4%	26.9%
– Vacuum extraction	12.5%	8.1%	6.2%	10.3%
– Forceps extraction	6.2%	22.0%	15.6%	12.8%
– Cesarean section	47.9%	41.0%	43.8%	50.0%
Birth weight (g), mean (SD)	2,941.4 (522.0)	2,863.3 (475.7)	2,580.4 (616.9)	2,355.2 (635.8)	<0.001
Birth weight z-score, mean (SD)	0.37 (0.90)	0.23 (0.82)	−0.25 (1.06)	−0.64 (1.09)	<0.001
Apgar score at 5 minutes, mean (SD)	9.2 (1.0)	9.2 (1.2)	8.9 (1.8)	8.5 (2.1)	0.02

Abbreviation: WHO, World Health Organization.

Table 2 Adverse events according to the modified WHO classification

	N (%)	Modified WHO classification N=331				p-value
		Class I (N=48) (%)	Class II (N=173) (%)	Class III (N=32) (%)	Class IV (N=78) (%)
Maternal cardiovascular events
Congestive heart failure	70 (21.1)	2.1	11.0	25.0	53.8	<0.001
Arrhythmia	15 (4.5)	2.1	1.2	6.3	12.8	<0.001
Thromboembolism	4 (1.2)	0	0	6.3	2.6	0.01
Infective endocarditis	1 (0.3)	0	0.6	0	0	0.82
Worsening of at least two NYHA functional classes	61 (18.4)	2.1	12.1	18.8	42.3	<0.001
Surgical intervention	15 (4.5)	0	3.5	0	11.5	0.004
Maternal death	12 (3.6)	0	0	0	15.4	<0.001
Any cardiovascular event	80 (24.2)	4.2	15	25	56.4	<0.001
Offspring events
Stillbirth	4 (1.2)	0	1.2	0	2.6	0.54
Early neonatal death	4 (1.2)	2.1	0	3.1	2.6	0.20
Preterm birth	74 (22.4)	6.2	15	37.7	42.3	<0.001
Small for gestational age	43 (13.0)	6.2	7.5	12.5	29.5	<0.001
Low birth weight	98 (29.6)	14.6	20.2	34.4	57.7	<0.001
Low Apgar score (<7) at 5 minutes	14 (4.2)	2.1	2.3	6.2	9.0	0.08
Neonatal intensive care unit admission	58 (17.5)	10.4	9.8	25.0	35.9	<0.001

Abbreviations: NYHA, New York Heart Association; WHO, World Health Organization.

Table 3 Adverse events according to the modified WHO classification in congenital and acquired heart diseases

	Congenital heart disease						Acquired heart disease
	Modified WHO classification N=157						Modified WHO classification N=174
	N (%)	Class I (N=42) (%)	Class II (N=81) (%)	Class III (N=2) (%)	Class IV (N=32) (%)	p-value	N (%)	Class I (N=6) (%)	Class II (N=92) (%)	Class III (N=30) (%)	Class IV (N=46) (%)	p-value
Maternal cardiovascular events
Congestive heart failure	21 (13.4)	2.4	8.6	50	37.5	<0.001	49 (22.8)	0	13.0	23.3	65.2	<0.001
Arrhythmia	0	0	0	0	0		15 (8.6)	16.7	2.2	6.7	21.7	0.001
Thromboembolism	1 (0.6)	0	0	0	3.1	0.27	3 (1.7)	0	0	6.7	2.2	0.11
Infective endocarditis	0	0	0	0	0		1 (0.6)	0	1.1	0	0	0.83
Worsening of at least two NYHA functional classes	16 (10.2)	2.4	9.9	0	21.9	0.05	45 (25.9)	0	14.1	20	56.5	<0.001
Surgical intervention	2 (1.3)	0	1.2	0	3.1	0.70	13 (7.5)	0	5.4	0	17.4	0.02
Maternal death	5 (3.2)	0	0	0	15.6	<0.001	7 (4.0)	0	0	0	15.2	<0.001
Any cardiovascular event	23 (14.6)	2.4	11.1	50	37.5	<0.001	57 (32.8)	16.7	18.5	23.3	69.6	<0.001
Offspring events
Stillbirth	1 (0.6)	0	1.2	0	0	0.83	3 (1.7)	0	1.1	0	4.3	0.44
Early neonatal death	2 (1.3)	2.4	0	0	3.1	0.50	2 (1.1)	0	0	3.3	2.2	0.42
Preterm birth	26 (16.6)	7.1	9.9	100	40.6	<0.001	48 (27.6)	0	19.6	33.3	43.5	0.009
Small for gestational age	19 (12.1)	4.8	8.6	50	28.1	0.004	24 (13.8)	16.7	6.5	10.0	30.4	0.002
Low birth weight	41 (26.1)	14.3	17.3	10.0	59.4	<0.001	57 (32.8)	16.7	22.8	30.0	56.5	0.001
Low Apgar score (<7) at 5 minutes	5 (3.2)	2.4	2.5	0	6.2	0.74	9 (5.2)	0	2.2	6.7	10.9	0.16
Neonatal intensive care unit admission	25 (15.9)	11.9	9.9	50	34.4	0.006	33 (19.0)	0	9.8	23.3	37.0	0.001

Abbreviations: NYHA, New York Heart Association; WHO, World Health Organization.