We analyzed the 2022 Merative MarketScan Research Commercial Database to determine the proportion of 18- to 49-year-old women receiving syphilis screening during pregnancy. In 2022, the US Census estimated that 65% of the population with health insurance were covered with private health insurance, and of those 56.6% were covered under employer-based coverage.^12,13 Merative MarketScan (www.Merative.com) databases are U.S. health care claims data available for health care research that are de-identified to the patient-level for 273 million patients. The commercial database did not include any pregnant women enrolled in Medicaid.

We created the analysis sample by merging multiple datasets on a unique identifier capturing physician visits and hospital visits, providing an all-inclusive experience during the woman’s pregnancy. Standardized medical codes, women’s age, and sex assigned at birth were utilized to identify pregnancy, childbirth, and services related to the pregnancy. We included codes from the International Classification of Diseases, Tenth Revision, Healthcare Common Procedure Coding System (HCPCS), and Current Procedural Terminology (CPT) to identify pregnancy and services provided during pregnancy.¹⁴ The final dataset was restricted to women aged 18 to 49 years, who were enrolled in a health plan for 8 months or more before documented pregnancy delivery, and who had at least one pregnancy claim in 2022.

Age was calculated at the time of pregnancy claim related to the pregnancy outcome, and then aggregated into specific age rages. Age ranges 18–24, 25–34, 35–44, and 45–49 years were selected according to the US Census Bureau age categories. The location for the woman was determined by the geographic location of the primary beneficiary’s residence. States were aggregated according to the Centers for Medicare & Medicaid Services (CMS) regions, 1 to 10 (Appendix).¹⁵ Employee classifications were aggregated as follows: Salary Non-union, Salary Union, Salary Other coded as Salary; Hourly Non-union, Hourly Union, Hourly Other coded as Hourly; Non-union, Union, and unknown. The types of health care insurance plans included are health maintenance organizations (HMO); preferred provider organizations (PPO); noncapitated point-of-service and capitated or partially capitated point-of-service, which were combined for a total point-of-service category (POS); consumer-driven health plan (CDHP); high-deductible, health plan (HDHP); and basic/major medical, comprehensive, and exclusive provider organization were coded as “Other.”

Syphilis screening was determined with CPT and HCPCS codes (Appendix). The trimesters were identified using previously published methods for diagnosis codes identifying gestation weeks.¹⁴ The trimesters were assigned as first trimester (0–13 weeks), second trimester (≥14–27 weeks), or third trimester (≥28 weeks). Syphilis screening categories were created according to the timing of syphilis screening (first, second, third trimester, any trimester). The counts and percentages of the pregnant women are not mutually exclusive per trimester, and a woman could have received screening during the 3 trimesters and counted for each trimester. We compared the syphilis screening categories stratified by demographics, CMS regions, and states with and without the legal requirement (statute or regulation) for syphilis screening during pregnancy in 2022 (Appendix). Descriptive statistics were used to describe demographic variables, and logistic regression models were used for odds ratios (ORs) using SAS 9.4 software (SAS Institute Inc., Cary, NC).

The regression reference categories were selected for the following reasons: 45- to 49-year-old pregnant women have higher chance of complications during a pregnancy and may be monitored closely during pregnancy¹⁶; CMS region 4 contains multiple southern states, which have historically higher rates of syphilis; salaried employees may have greater health care access; and PPO health plans typically allow for the greatest level of access.¹⁷

The analysis dataset contains pregnancy outcome claims data from 2022 and syphilis screening for those identified outcomes ending on December 31,2022. These data involve deidentified patient claims and are considered a secondary data source; thus, no institutional review board (IRB) approval was required.

For the time period of January 1, 2022, through December 31, 2022, we identified 170,005 commercially insured pregnant women between the ages of 18 and 49 years. The 170,005 pregnant women were most commonly in the 25 to 34 years of age group (62.6%), residents of CMS region 4 (30.1%), salaried employees (29.3%), and participants in a PPO health plan (47.3%). Syphilis screening rates by trimester increased from the first (52.8%), second (64.3%), to third (72.1%). Although nonsignificant, women aged 18 to 24 years were screened the least during their pregnancy (first: 49.6%, second: 62.9%, third: 70.4%) compared with other women and overall, 77.0% (Table 1). In addition, of the 135,376 women who were screened for syphilis, 83.8% (results not shown) were screened at least twice during their pregnancy; for example, a patient may have received a test in the first and third trimesters.

The percentage of pregnant women screened at least once for syphilis exceeded 75% in all 10 CMS regions, ranging from 75.7% to 85.7%. The CMS regions’ screening percentages during the first trimester ranged from 46.5% (region 9) to 58.6% (region 3). Syphilis screening increased by an average of 11 percentage points during the second trimester, with region 6 having the largest increase between the first and second trimesters, from 48.2% to 64.1% (Table 1). Again, syphilis screening increased in the third trimester, ranging from 65.9% in region 8 to 81.1% in region 6.

By employee classification, although workers participating in a union received the highest screening during all trimesters, with 83.2% (data not shown, representing 1.9% of the total sample) screened at least once during pregnancy. Consumer-driven health plans had the highest percentage of pregnant people being screened at least once for syphilis at 80.6%, compared with the other health plans.

Forty-two of the 50 states require syphilis screening during pregnancy. Of the pregnant women in our sample 95.1% (144,731) resided in a state requiring syphilis screening within the first trimester or at the first available prenatal visit and 10.4% (17,749) were missing geographic location data. Of the 144,731, only 80% of those residing in states with laws were screened for syphilis during this time frame. In addition, 22 states required screening during the third trimester, and 73% of the patients in those states did not receive a screening during the third trimester (Tables 2, 3; Appendix). Overall, states with any screening laws reported 80.2% receiving screening compared with states with no laws, 77.9%. The screening laws had 14% greater odds (OR, 1.14; 95% confidence interval [CI], 1.08–1.21) at receiving a screening for syphilis compared with a jurisdiction without laws.

The odds of receiving a syphilis screening in states with state laws varied compared with the reference category. Region 4 contains multiple southern states that have historically higher rates of syphilis. Region 6’s odds were greater (OR, 1.63; 95% CI, 1.56–1.71) for being screened at least once during pregnancy compared with Region 4; followed by Region 7, 36% greater odds (OR, 1.36; 95% CI, 1.27–1.45), and Region 5 displaying a slight increase, 6% greater odds (OR, 1.06; 95% CI, 1.01–1.11) compared with Region 4 (Table 3). Region 8 had 15% lower odds (OR, 0.85; 95% CI, 0.79–0.91), and Region 9 had 13% lower odds (OR, 0.87; 95% CI, 0.84–0.91) of receiving a syphilis test any time during their pregnancy compared with Region 4 (Table 3). Pregnant women who were classified as hourly worker had 11% lower odds (OR, 0.89; 95% CI,0.86–0.92) of receiving a syphilis screening than pregnant women working in a salaried position. The type of insurance plan in which a woman was enrolled was not strongly associated with the receipt of at least one syphilis screening during pregnancy. Women enrolled in a CDHP had higher odds (OR, 1.07; 95% CI, 1.02–1.11) of being screened for syphilis during pregnancy compared with PPO plans (reference category).

Screening for syphilis during pregnancy is recommended by many professional organizations and is required by law in most states in the United States, yet 20% of pregnant women do not have evidence of any screening for syphilis in the claims data. The highest percentage of pregnant women was screened during the third trimester, and the majority of those screened received at least 2 tests during pregnancy. However, the data show wide-spread non-adherence to the recommendations to perform syphilis screening at the first prenatal visit. Furthermore, the different types of commercial health insurance plans demonstrated minor differences in syphilis screening rates. It is noted that, even with health insurance coverage and state mandates, there are women who are not receiving the recommended syphilis screenings during their pregnancy, which points to missed opportunities to provide quality care.

The need for a better understanding of these missed opportunities and ways to overcome the potential barriers to receiving quality care during pregnancy cannot be overstated. This is highlighted by a recent study stating that 36.8% of birthing women delivering an infant with CS received no prenatal care.⁸ How prenatal care is delivered warrants attention to ensure no newborn or pregnant woman experiences negative health outcomes from missed opportunities.¹⁸ The commercially insured population has access to health care, yet there remains room for improvement to reach the optimal level of syphilis screening to help reduce cases of CS.

A study by Lanier et al.¹⁹ investigated syphilis screening in 6 southern states and demonstrated first-trimester screening percentages were higher than the third-trimester percentages, in comparison to our findings where third-trimester screening percentages were higher. The screening percentages increased from first to third trimester, with pregnant women receiving syphilis screening during the third trimester at a much higher percentage: first, 52.8%; third, 72.1%. However, the study by Lanier and colleagues was focused solely on Medicaid enrollees, and the dynamics of receiving care in this cohort is markedly different than our study cohort. The difference in percentages between the first and third trimesters may represent missed opportunities for clinical intervention, especially considering that 42 states have prenatal screening requirements.

In all CMS regions, more than 75% of the women received at least one syphilis screening during their pregnancy. In addition, states with laws requiring screening at any time during the pregnancy had higher screening percentages compared with states without any laws. The importance of syphilis screening during prenatal care continues to drive an important message that CS is preventable.

Health care access is vital for ensuring a safe pregnancy and was operationalized in our study by showing enrollment in the different types of health insurance plans. Differences in plan types were expected because of the variances in access to providers, and managed care practices have on meeting quality metrics. Mick and colleagues²⁰ found that patients enrolled in managed care plans were less likely to receive sexually transmitted infection testing by primary care providers compared with the accountable care organization–driven plans that have incentives for primary care providers to coordinate care across their patient panels. This contrasted with our findings with nonsignificant differences between the private insurance plans. However, our analyses were not able to identify specific incentives for quality in each of the defined health plan types, such as accountable care organization affiliation.

Our analyses have main limitations that are inherent when using commercially insured medical claims data. The data are subject to coding errors, especially if the provider used ambiguous codes to identify syphilis screening.^21–23 MarketScan databases are collected as a convenience sample from large employers that provide private insurance to employees and may not be representative of the US population.^24,25 Furthermore, it was estimated in 2021 that 96% of pregnant women had health care coverage for their delivery, with 51.7% covered by commercial insurance, 41.0% by Medicaid, 3.4% by other coverage, and 3.9% with self-pay, possibly also uninsured at the time of delivery.²⁶ In addition, Hammerslag et al.²⁷ documented pregnant women enrolled in Medicaid had higher odds of screening at any time during pregnancy. Also, the analysis did not include the location of treatment and if effective treatment was offered and administered.

Access to quality sexually transmitted infection care is important for reducing the burden of CS. Sexually transmitted infections can be diagnosed and treated in many different venues, including emergency departments and urgent care clinics,^28,29 and these health care access events may be the only opportunity to provide syphilis prevention and education for some pregnant women who have reduced access to care. Pregnant women also may receive prenatal care for the first time at labor and delivery because they did not access prenatal care otherwise. Therefore, the need for public health messaging (e.g., “Talk.Test.Treat.”) around syphilis knowledge and screening recommendations will require a holistic approach among medical providers, patients, and public health departments to create a team effort for ensuring healthy pregnancies.³⁰ Despite near-universal prenatal syphilis screening requirements across states, not all women are receiving recommended syphilis screening during pregnancy. Therefore, there is room for improvement that necessitates public health professionals, medical providers, and patients working together to ensure improved health outcomes during pregnancy. Adherence to recommended syphilis screening, reaching pregnant women during all health care visits, and enhanced public health messaging can help achieve the larger goal of ensuring the health of future generations.