Associations between hypothyroidism and adverse obstetric and neonatal outcomes: a study of a population database including over 184,000 women with hypothyroidism

Figures & data

Figure 1. Prevalence of Hypothyroidism disease among women who gave birth between 2004 and 2014.

Table 1. Maternal characteristics.

Characteristics	Hypothyroidism N = 184,869	No Hypothyroidism N = 8,911,919	p-value
Age (years)
<25	13.5%	38.5%	<0.001
25–34	56.2%	47.1%
≥35	30.3%	14.4%
Race
White	70.3%	51.9%	<0.001
Black	4.3%	13.9%
Hispanic	12.9%	23.4%
Asian and Pacific	6.7%	5.1%
Native American	0.7%	0.8%
Other	5.0%	4.8%
Income quartiles
Less than 39,000	16.5%	27.6%	<0.001
$39,000-47,999	21.7%	25.5%
$48,000-62,999	26.8%	24.8%
$63,000 or more	35.0%	22.1%
Medical Insurance Plan type
Medicare	0.9%	0.6%	<0.001
Medicaid	20.0%	43.1%
Private including Health Maintenance Organization	74.5%	50.2%
Self-Pay	1.6%	3.2%
No charge	0.1%	0.2%
Other	2.9%	2.7%
Hospital type
Rural	11.9%	14.2%	<0.001
Urban	88.1%	85.8%
Body mass index
Obese (≥30)	3.5%	7.4%	<0.001
Previous cesarean section	20.7%	15.9%	<0.001
In vitro fertilization pregnancy	0.7%	0.1%	<0.001
Chronic hypertension	4.2%	1.8%	<0.001
Pregestational diabetes mellitus	3.6%	0.9%	<0.001
Illicit Drug use	0.7%	1.4%	<0.001
Human immunodeficiency virus	0%	0%	<0.001
Tobacco Smoking	3.4%	4.9%	<0.001
Multiple gestation	3.0%	1.5%	<0.001

Table 2. Pregnancy and delivery outcomes.

Outcomes	Hypothyroidism (%)	No Hypothyroidism (%)	Crude OR (95% CI)	Adjusted OR (95% CI)	Adjusted p-value
Pregnancy outcomes^a
Pregnancy induced hypertension	9.9%	7.4%	1.390 (1.368–1.411)	1.188 (1.150–1.227)	<0.001
Gestational hypertension	4.3%	3.3%	1.315 (1.286–1.346)	1.168 (1.115–1.223)	<0.001
Preeclampsia	4.6%	3.6%	1.308 (1.279–1.337)	1.215 (1.160–1.272)	<0.001
Eclampsia	0.1%	0.1%	0.832 (0.694–0.998)	1.048 (0.689–1.593)	0.827
Preeclampsia and Eclampsia superimposed hypertension	1.1%	0.5%	2.178 (2.083–2.277)	1.058 (0.955–1.173)	0.279
Gestational diabetes mellitus	10.3%	5.7%	1.923 (1.894–1.953)	1.428 (1.383–1.474)	<0.001
Placenta previa	0.8%	0.5%	1.529 (1.453–1.609)	1.154 (1.037–1.285)	0.009
Delivery outcomes^b
Preterm premature rupture of membranes	1.4%	1.1%	1.216 (1.169–1.265)	1.186 (1.091–1.290)	<0.001
Preterm delivery	8.3%	7.2%	1.173 (1.153–1.193)	1.122 (1.077–1.168)	<0.001
Abruptio placenta	1.1%	1.1%	1.028 (0.984–1.074)	1.037 (0.942–1.142)	0.462
Chorioamnionitis	1.7%	1.8%	0.945 (0.912–0.979)	1.088 (1.014–1.167)	0.019
Operative vaginal delivery	6.4%	6.5%	0.989 (0.970–1.007)	1.036 (0.994–1.079)	0.096
Cesarean section	41.8%	32.1%	1.516 (1.502–1.531)	1.206 (1.176–1.236)	<0.001
Spontaneous vaginal delivery	53.5%	62.5%	0.691 (0.685–0.698)	0.847 (0.827–0.867)	<0.001
Hysterectomy	0.1%	0.1%	1.823 (1.610–2.064)	1.424 (1.127–1.799)	0.003
Postpartum hemorrhage	3.1%	2.9%	1.062 (1.034–1.091)	1.072 (1.015–1.131)	0.012
Wound complications	0.5%	0.4%	1.517 (1.424–1.616)	1.113 (0.957–1.295)	0.166
Maternal death	0.0%	0.0%	0.923 (0.521–1.634)	0.708 (0.172–2.921)	0.633
Transfusion	1.1%	1.0%	1.126 (1.078–1.176)	1.122 (1.029–1.224)	0.009
Others
Maternal infection	2.0%	2.2%	0.921 (0.892–0.952)	1.084 (1.015–1.158)	0.017
Deep vein thrombosis	0.1%	0.0%	1.503 (1.250–1.809)	1.353 (0.920–1.991)	0.125
Pulmonary embolism	0.0%	0.0%	1.620 (1.235–2.125)	1.309 (0.743-2.308)	0.352
Venous thromboembolism	0.1%	0.1%	1.545 (1.323–1.804)	1.315 (0.948–1.824)	0.101
Disseminated intravascular coagulation	0.2%	0.2%	1.253 (1.142–1.375)	1.199 (1.003–1.433)	0.046

^aPregnancy outcome: adjust for age, race, medical insurance plan type, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, human immunodeficiency virus, multiple gestation, pregestational diabetes mellitus, in vitro fertilization, hospital type and income.

^bDelivery outcomes: adjust for age, race, medical insurance plan type, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, human immunodeficiency virus, multiple gestation, pregestational diabetes mellitus, in vitro fertilization, hospital type, income, pregnancy induced hypertension, gestational hypertension, preeclampsia, gestational diabetes mellitus and placenta previa.

Table 3. Neonatal outcomes^a.

Outcomes	Hypothyroidism (%)	No Hypothyroidism (%)	Crude OR (95% CI)	Adjusted OR (95% CI)	Adjusted p-value
Small for gestational age infants	2.6%	2.2%	1.213 (1.179–1.249)	1.202 (1.136–1.273)	<0.001
Intrauterine fetal death	0.4%	0.4%	0.968 (0.900–1.040)	1.021 (0.876–1.190)	0.788
Congenital Anomalies	0.8%	0.4%	1.906 (1.808–2.009)	1.342 (1.219–1.477)	<0.001

^aFetal outcomes: adjust for age, race, medical insurance plan type, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, human immunodeficiency virus, multiple gestation, pregestational diabetes mellitus, in vitro fertilization, hospital type, income, pregnancy induce hypertension, gestational hypertension, preeclampsia, gestational diabetes mellitus and placenta previa.

Data Availability Statement

The data that support the findings of this study are publicly available in NIS Database Documentation at https://www.hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp.