Association between gestational age at delivery and indicator-specific severe maternal morbidity

Figures & data

Table 1. Maternal characteristics in deliveries with and without severe maternal morbidity stratified by gestational age.

	Deliveries without SMM	All Deliveries with SMM	Deliveries <28 weeks with SMM	Deliveries 28–36 weeks with SMM	Deliveries 37 weeks with SMM
Maternal characteristics	(n = 148,942)	(n = 3742)	(n = 256)	(n = 1239)	(n = 2247)
Age (years)	29 ± 5.9	29 ± 6.4	28 ± 6.3	30 ± 6.6	29 ± 6.3
Age <20	9229 (6)	257 (7)	15 (6)	88 (7)	154 (7)
Age >35	26,327 (18)	808 (22)	52 (20)	295 (24)	461 (21)
Primiparous	82,001 (55)	1930 (52)	115 (45)	533 (43)	1,164 (52)
Race/ethnicity
Non-Hispanic White	110,550 (74)	2397 (64)	151 (59)	811 (66)	1,436 (64)
Non-Hispanic Black	29,454 (20)	1098 (29)	97 (38)	362 (29)	639 (28)
Other	8978 (6)	247 (7)	8 (3)	66 (5)	173 (8)
Marital status
Unmarried	62,182 (42)	1990 (53)	164 (64)	707 (57)	1119 (50)
Married	86,800 (58)	1752 (47)	92 (36)	532 (43)	1128 (50)
Insurance
Private	82,718 (56)	1713 (46)	96 (38)	545 (44)	1072 (48)
Public	38,658 (26)	1518 (40)	126 (49)	565 (46)	827 (37)
Self-pay/ other	27, 602 (18)	511 (14)	34 (13)	129 (10)	348 (15)
Preexisting hypertension	4173 (3)	478 (13)	51 (20)	262 (21)	165 (7)
Preexisting diabetes	1845 (1)	249 (7)	18 (7)	138 (11)	93 (4)
Pregnancy induced hypertension	17,617 (12)	1499 (40)	97 (38)	746 (60)	656 (29)
Delivery mode
Vaginal delivery	109,608 (73)	1503 (40)	121 (47)	468 (38)	914 (41)
Cesarean delivery	39,914 (27)	2239 (60)	135 (53)	771 (62)	1334 (59)

Data are listed as n (%), mean ± standard deviation.

Figure 1. Predicted probability of severe maternal morbidity by gestational age in an adjusted model. Gestational age is represented as a continuous variable. Confounders adjusted for include age, race, insurance status, marital status, parity, and preexisting hypertension or diabetes.

Table 2. Indicator-specific severe maternal morbidity stratified by gestational age epoch.

SMM Diagnostic Criteria	All Cases of SMM	Deliveries <28 weeks with SMM	Deliveries 28–36 weeks with SMM	Deliveries >37 weeks with SMM
	(n = 3742)	(n = 256)	(n = 1,239)	(n = 2247)
Amniotic fluid embolism	8 (0.2)	0 (0)	3 (0.2)	5 (0.2)
Acute myocardial infarction	6 (0.2)	2 (0.8)	1 (0.1)	3 (0.1)
Aneurysm	10 (0.3)	0 (0)	1 (0.1)	9 (0.4)
Blood transfusion	1348 (36)	86 (34)	348 (28)	915 (41)
Cardiac arrythmia	139 (3.7)	2 (0.8)	21 (1.7)	116 (5.2)
Cardiac conversion	13 (0.4)	1 (0.4)	6 (0.5)	6 (0.3)
Cerebrovascular disorder	70 (1.9)	4 (1.6)	20 (1.6)	46 (2.0)
Disseminated intravascular coagulation	182 (4.9)	14 (5.5)	57 (4.6)	111 (4.9)
Eclampsia	96 (3.6)	6 (2.3)	45 (3.6)	45 (2.0)
Heart failure	375 (10)	16 (6.3)	79 (6.4)	280 (13)
Hysterectomy	190 (5.1)	9 (3.5)	95 (7.7)	86 (3.8)
Pulmonary edema	97 (2.6)	10 (3.9)	49 (4.0)	38 (1.7)
Acute renal failure	221 (5.9)	26 (10)	105 (8.5)	90 (4.0)
Respiratory distress syndrome	133 (3.6)	17 (6.6)	58 (4.7)	58 (2.6)
Sepsis	125 (3.3)	36 (14)	38 (3.1)	51 (2.3)
Shock	133 (3.6)	16 (6.3)	40 (3.2)	77 (3.4)
Sickle cell crisis	28 (0.8)	1 (0.4)	10 (0.8)	17 (0.8)
Air or thrombotic embolism	59 (1.6)	3 (1.2)	25 (2.0)	31 (1.4)
Temporary tracheostomy	1 (0.03)	0 (0)	1 (0.1)	0 (0)
Mechanical ventilation	74 (2.0)	12 (4.7)	27 (2.2)	35 (1.6)

Data are listed as n (%). Some cases have more than one diagnosis during the associated delivery admission and thus the column per cent does not total 100.