Maternal and Fetal Outcomes Among Women with Depression

Abstract

Objective:

To compare maternal and fetal outcomes among women with and without diagnosed depression at the time of delivery.

Methods:

Hospital discharge data from the 1998–2005 Nationwide Inpatient Sample (NIS) were used to examine delivery-related hospitalizations for select maternal and fetal outcomes by depression diagnosis.

Results:

The rate of depression per 1000 deliveries increased significantly from 2.73 in 1998 to 14.1 in 2005 (p < 0.001). Women diagnosed with depression were significantly more likely to have cesarean delivery, preterm labor, anemia, diabetes, and preeclampsia or hypertension compared with women without depression. Fetal outcomes significantly associated with maternal depression were fetal growth restriction, fetal abnormalities, fetal distress, and fetal death.

Conclusions:

These findings suggest that depression is associated with adverse maternal and fetal outcomes. Our results provide additional impetus to screen for depression among women of reproductive age, especially those who plan to become pregnant.

Introduction

Depression is a mood disorder that is prevalent among women of childbearing age.^1,2 The estimated prevalence of depression at different times during pregnancy is reported to range from 7.4% to 15%.^3
–5 Depression has important clinical implications for the health status of the mother during pregnancy that might influence the occurrence of adverse maternal and fetal outcomes. First, depression among pregnant women is associated with functional impairment and harmful health behaviors, such as self-medication, alcohol and substance abuse, cigarette use, poor nutrition and inadequate weight gain, suicide, and delayed or inadequate use of prenatal care.^1,2,4,6,7 Second, placental corticotrophin-releasing hormone (CRH), predominantly secreted in the latter half of pregnancy, may influence placental function and uterine blood flow, thus possibly contributing to adverse maternal and fetal outcomes, such as premature delivery and low birth weight.^2,8,9

The few studies that have addressed the relationship between maternal depression and pregnancy outcomes have yielded conflicting evidence on the presence or absence of an association with suboptimal birth outcomes, such as preterm labor or delivery, low birth weight, fetal growth restriction, hypertension, and operative delivery, including cesarean sections.^{2,10

–16} The inconsistent results can be explained by problems with generalizability because of differences in the type of depression (major or minor, or both), the assessment of depression, the measurement of depression at different times during pregnancy, varied study populations, and small sample sizes.^3,16 Also, high rates of prenatal care among study participants as a result of recruitment in prenatal institutions in the majority of these studies might have diluted the true associations. In addition, very limited information is available from studies in the United States. Thus, further examination of depression and its relationship to pregnancy and obstetric outcomes is needed.

The purpose of this study was to provide national estimates of the burden of diagnosed depression among women residing in the United States at the time of delivery and to compare demographics, hospital characteristics, pregnancy complications, and obstetric outcomes for women with and without depression who are hospitalized for delivery.

Materials and Methods

We used hospital discharge data from the Nationwide Inpatient Sample (NIS), one of a family of databases and software tools developed as part of the Healthcare Cost and Utilization Project (HCUP),¹⁷ sponsored by the Agency for Healthcare Research and Quality (AHRQ) in partnership with state-level data-collection organizations to provide nationwide estimates of inpatient care. The NIS is a stratified sample of approximately 20% of all U.S community hospitals as defined by the American Hospital Association (AHA). Hospitals are selected on the basis of five characteristics: rural or urban location, number of beds, region, teaching status, and ownership. The NIS includes all discharges from the selected hospitals and provides information on 5–8 million discharges from an average of 1000 hospitals each year.¹⁷ It is the largest all-payer database that, when weighted, provides nationwide estimates of hospital inpatient care in the United States.

Data were analyzed from NIS for 1998–2005. Because the NIS contains sample data and does not contain personal identifiers, the institutional review board of the Centers for Disease Control and Prevention (CDC) determined that this research was exempt from review. All analyses were duplicated independently and reviewed internally for compliance with AHRQ's data use agreement.

Our analysis included all women aged 15–44 years with a delivery hospitalization, with the exception of those who had an abortion or an ectopic or a molar pregnancy. Delivery hospitalizations were identified using a previously documented enhanced method.¹⁸ The International Classification of Diseases, Ninth Revision, Clinical Modifications (ICD-9-CM)¹⁹ was used to identify concurrent diagnoses at time of delivery for the following: depression, ICD-9-CM codes 296.2, 296.3, 300.4, 311, 298.0, 309.0, and 309.1; alcohol or substance abuse, ICD-9-CM codes 291, 292, 303–305, 648.3, 655.5, 965.0, and V65.42; other mental disorders (anxiety, adjustment, eating, mood, personality, and psychotic disorders), ICD-9-CM codes 295–298, 293.81–84, 300, 301, 307.1, 307.51, 309.24, 309.28, 309.3, 309.4, and 309.9; preterm labor, ICD-9-CM codes 644.0 and 644.2; preeclampsia or hypertension, ICD-9-CM code 642; diabetes, ICD-9-CM codes 250, 648.0, 648.8, 790.29, and 791.5; cesarean delivery, ICD-9-CM procedure codes 74.0, 74.1, 74.2, 74.4, 74.99; anemia, ICD-9-CM codes 648.2, 280–285; placental abnormalities (placenta previa, abruptio, and accreta), ICD-9-CM code 641.0–2, 667; genitourinary tract infections, ICD-9-CM codes 646.6, 590, 595, 597, 599.0, and 614–616; infections during labor, ICD-9-CM codes 658.2, 658.4, 659.2, and 659.3; fetal growth restriction, ICD-9-CM code 656.5; fetal abnormalities, ICD-9-CM codes 655.0 and 655.3–5; fetal distress, ICD-9-CM codes 656.3, 656.8, and 659.7; and fetal death, ICD-9-CM code 656.4.

Chi-square tests with a significance level of 0.05 were used to compare the prevalence of depression by sociodemographic and hospital characteristics, including age in years, insurance status (a proxy for socioeconomic status [SES]), hospital location, and region. Student's t tests were used to compare the mean length of hospital stay and hospital charges. Values for charges were adjusted for inflation for the period 1998–2005 by using the Consumer Price Index (CPI),²⁰ and as a result, mean charges are reported in 2005 dollars. Rates of hospitalizations per 1000 deliveries were assessed for all outcomes of interest by depression diagnosis, and changes in the rates of depression for the period 1998–2005 were evaluated. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the likelihood of pregnancy complications and obstetric outcomes during delivery hospitalizations by depression diagnosis while adjusting for sociodemographic and hospital characteristics. Alcohol or substance abuse was not evaluated as a potential confounder because it did not alter the OR for the outcomes of interest by ≥10%. All statistical analyses were conducted using SAS-callable SUDAAN (Research Triangle Institute, Research Triangle Park, NC) to account for the complex sampling design of the NIS.

Results

We identified an estimated 32,156,438 delivery hospitalizations among women 15–44 years of age in the United States during the period 1998–2005. Of these hospitalizations, 244,939 had a depression diagnosis, thus accounting for an overall rate of depression of 7.62/1000 delivery hospitalizations. The rate of depression increased significantly during the 7-year period, from 2.73/1000 deliveries in 1998 to 14.12/1000 deliveries in 2005 (p for trend <0.001) (Fig. 1). Rates of depression increased regardless of age, insurance status, or region (data not shown).

FIG. 1.

Rate of diagnosed depression among delivery hospitalizations among women 15–44 years of age, 1998–2005 Nationwide Inpatient Sample, United States.

The rates of depression among women with delivery hospitalizations increased with maternal age, from 6.8/1000 deliveries for women 15–24 years of age to 9.6/1000 deliveries for women 35–44 years of age (Table 1). No significant differences were observed by hospital location (rural vs. urban), but rates of depression varied by hospital region: the highest rate was in the Northeast (10.0/1000 deliveries), followed by the Midwest (9.5/1000 deliveries), and then the South and West (each with 6.3/1000 deliveries). Rates were also higher among those uninsured (8.3/1000 deliveries), those with other mental disorders (222.2/1000 deliveries), and those with alcohol or substance abuse problems (38.5/1000 deliveries) (Table 1). In addition, women with a depression diagnosis had significantly longer mean length of stay (3.18 vs. 2.53 days, p < 0.001) and higher mean hospital charges ($9181 vs. $7847, p < 0.001) compared with those without a depression diagnosis.

In multivariable regression analysis, after adjusting for age, insurance status, and hospital characteristics, we found that women hospitalized for a delivery with a depression diagnosis were more likely to have several adverse maternal outcomes, including preterm labor, preeclampsia, diabetes, cesarean section, anemia, and placental abnormalities, as well as infectious complications, such as genitourinary tract infections and infections during labor (Table 2). In addition, we observed that these women experienced a higher rate of adverse fetal outcomes, such as fetal growth restriction, fetal abnormalities, fetal distress, and fetal death (Table 2).

Table 1.

Estimated Numbers and Rates of Diagnosed Depression by Demographic and Hospital Characteristics Among Delivery Hospitalizations, 1998–2005 Nationwide Inpatient Sample, United States

Characteristic	Total deliveries	Deliveries with diagnosed depression	Rate ^a	p value
Age in years
15–24	11,443,760	78,083	6.8	<0.001
25–34	16,229,486	123,743	7.6
35–44	4,483,192	43,113	9.6
Insurance status
Insured	18,143,477	128,852	7.1	<0.001
Uninsured	13,927,436	115,676	8.3
Location of hospital
Urban	27,941,759	212,802	7.6	0.92
Rural	4,184,721	32,025	7.7
Region of hospital
Northeast	5,515,225	55,362	10.0	<0.001
Midwest	6,980,306	66,331	9.5
South	11,775,061	73,760	6.3
West	7,882,847	49,486	6.3
Other mental disorders
Yes	164,493	36,551	222.2	<0.001
No	31,991,945	208,389	6.5
Alcohol/substance abuse
Yes	1,098,915	42,332	38.5	<0.001
No	31,057,523	202,607	6.5

Per 1000 deliveries.

Table 2.

Estimated Numbers, Rates, and Adjusted Odds Ratios for Select Obstetric Complications Among Delivery Hospitalizations, with and without a Depression Diagnosis, 1998–2005, Nationwide Inpatient Sample, United States

	With depression		Without depression
Maternal and fetal outcomes	n	Rate ^b	n	Rate ^b	Odds ratio ^a (95%CI)
Preterm labor	28,962	118.2	2,302,057	72.1	1.71 (1.65–1.77)
Preeclampsia/hypertension	28,234	115.3	2,459,044	77.1	1.57 (1.52–1.62)
Diabetes	18,245	74.5	1,518,269	47.6	1.52 (1.47–1.58)
Cesarean delivery	79,057	322.8	8,297,749	260.0	1.34 (1.30–1.37)
Anemia	31,924	130.3	2,440,384	76.5	1.81 (1.73–1.89)
Placental abnormalities	8,018	32.7	672,956	21.1	1.53 (1.45–1.61)
Genitourinary tract infections	8,939	36.5	921,419	28.9	1.26 (1.18–1.34)
Infections during labor	11,976	48.9	1,337,605	41.9	1.19 (1.13–1.24)
Fetal growth restriction	6,004	24.5	500,854	15.7	1.58 (1.48–1.68)
Fetal abnormalities	640	2.6	29,948	0.9	2.75 (2.26–3.34)
Fetal distress	41,843	170.8	4,361,556	136.7	1.30 (1.25–1.35)
Fetal death	2,245	9.2	140,664	4.4	2.02 (1.83–2.22)

Comparing odds of obstetric complications among delivery hospitalizations with depression vs. those without depression, adjusted for age, insurance status, location and region.

Rates are per 1000 deliveries.

Discussion

This study provides nationwide estimates of rates of depression among women hospitalized for delivery in the United States. Our results indicate that the rate of depression coded during the delivery hospitalization increased 5-fold during the period 1998–2005. This could be the result of an increased awareness and diagnosis of depression during pregnancy or at the time of delivery. A recent study found that 44% of obstetrician/gynecologists screen for depression and that the majority exhibit a positive attitude toward this practice.²¹ These findings may also reflect the increasing trends of major depression among the general population.²² Our estimates of depression at the time of delivery are much lower than previously reported in the obstetric population.^1,2,4,5 This could be due to incomplete reporting and documentation of all comorbid conditions in the hospital record when the woman is hospitalized for a delivery.²³ Moreover, mental disorders during delivery hospitalization may be coded only if they interfere with management of the patient's condition or if significant care is required.²³ Thus, our estimated rate of depression as abstracted from the medical record during a delivery hospitalization may reflect the more severe depressive episodes rather than the prevalence of depression in pregnant women.

Women with a diagnosis of depression were consistently 1.2–2.8 times more likely to experience adverse maternal and fetal outcomes, spend more time in the hospital, and incur higher hospital charges. In agreement with previous studies on the prevalence of depression among pregnant women, and similar to other chronic conditions complicating pregnancy,^1,10 depression was associated with increasing age. The higher rate of depression among those uninsured may represent disadvantaged women of low SES, a well-established risk factor for depression.³ The finding that depression was significantly associated with increased hospital length of stay and total hospital charges further documents the economic burden of this disease. Of course, this might also have been because of the higher rates of adverse maternal and fetal outcomes observed among this population

Our results that showed a significant positive association of depression with preterm labor and fetal growth restriction support findings from previous studies.^10,12,13,24 Consistent with previous reports, our study results also indicate that women with depression had higher rates of fetal distress and fetal abnormalities.^16,25 Also in line with the results from other studies, we reported several adverse maternal outcomes, such as preeclampsia, placental abnormalities, anemia, and genitourinary tract infections.¹⁶ We, however, found higher rates of cesarean delivery among women with a diagnosis of depression, even though previous studies using hospital-level data found no association.^14,15 Although the nature of these adverse outcomes is not well understood, depression-related behaviors (poor dietary habits, suboptimal prenatal care, alcohol or substance abuse), placental CRH, genetic factors (familial and gene mutations), and their complex interplay with environmental factors (family dynamics and society) may play a role.^{1,2,4,6,7,9,26}

Our study has some limitations. First, because of the cross-sectional design, we could not assess the temporal relationship between depression and maternal and fetal outcomes, and, therefore, we could not infer causality. Second, the unit of analysis was the hospitalization rather than the individual patient; therefore, women with repeated delivery hospitalizations during the study period might have been counted more than once. Third, our analysis depended on hospital discharge data. The ICD-9-CM codes for comorbidities among obstetric populations, in general, have moderate to high specificity but low sensitivity, thus underestimating their prevalence. Also, because comorbidities are usually coded only if they interfered with management of the patient's condition or if significant care was required,²³ it is likely that only severe cases of depression were coded at the time of delivery. Although little is known about the prevalence of depression during delivery hospitalization, a recent study found that up to 10% of women from a group HMO practice were diagnosed with depression during pregnancy.⁵ Fourth, incomplete information on race limited our ability to differentiate cultural and ethnic influences on the diagnosis of depression. We lacked information on antidepressant use during pregnancy, and research indicates that antidepressants do cross the placenta during pregnancy and, therefore, could influence our findings. Given the few studies and their conflicting results on the presence or lack of an association between antidepressant use and adverse fetal outcomes, however, further research in this area is warranted.^27

–30

Depressive symptoms during pregnancy are associated with increased life stress, decreased social support, poor weight gain, alcohol/substance abuse, and low attendance at prenatal checkups.¹ In addition, results from this study document that depression increases the risk of several adverse maternal and fetal outcomes at the time of delivery. Depression during pregnancy is a known risk factor for postpartum depression,^31,32 and, therefore, the American College of Obstetricians and Gynecologists (ACOG) recommends antenatal screening for psychosocial risk factors, including depression.³³ A positive response to two simple screening questions for depression among pregnant women necessitates the need for further evaluation. After diagnosis, it is important to weigh the risks and benefits to both the fetus and mother and consider treatment options for the management of depression during pregnancy, including pharmacotherapy and psychotherapy.

This study demonstrates that during hospital delivery, the risk of maternal and fetal complications is significantly higher among women diagnosed with depression compared with those without depression. Given the substantial increase in such hospitalizations in our study, surveillance of maternal morbidity associated with depression should be continued. Because of the inherent limitations of hospital discharge data, future studies with detailed clinical data are needed to better understand the nature of our findings as well as to improve management and care of pregnant women with depression.

Footnotes

Acknowledgments

This report was presented in part at the Maternal and Child Health Epidemiology Conference in Atlanta, Georgia, December 2007. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Disclosure Statement

The authors have no conflicts of interest to report.

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