This was a descriptive study that employed a database of emergency medical transport response records for women of reproductive age using FirstWatch^® (Stout Solutions LLC, Encinitas, California, United States), a novel, web-based, commercially available surveillance software system used by the Centers for Disease Control and Prevention’s (CDC) El Paso Quarantine Station. The original purpose of the CDC system was to identify reportable diseases, such as tuberculosis, and improve disease surveillance at the El Paso, Texas POEs (16).

During December 2008–December 2009, EMS transport response records were identified for 143 women 12–49 years of age who had crossed into the United States at an El Paso POE (Table 1).

Ten women refused transport, electing instead to use their own transportation, and 133 were carried to an El Paso hospital. Most women (57.4%; 82/143) were under 25 years of age. Among the 127 women who reported country of residence, nearly 80% (No. = 101) resided in the United States, and the remainder, in Mexico (No. = 26). Most sought care for acute illnesses or injuries, but the most common single reason for requesting an EMS transport among these women of reproductive age was an obstetric emergency. Almost half (47.6%; 68/143) of the EMS calls from an El Paso POE were obstetric-related. The corresponding proportions in Texas in 2009 (18) and the City of El Paso in 2011 (19) were lower at 2.8% and 5.0%, respectively (P < 1 × 10⁻⁷) (Table 2).

A total of 154 women with obstetric conditions during December 2008–April 2011, of whom one-third were adolescents (52/154), requested EMS assistance from an El Paso POE (Table 3). The primary reason for the call, according to EMS response records, was labor. EMS records indicated that 6 of the 154 women (3.9%) refused EMS ambulance transport to a hospital. Hospital records for 5 of these 6 women, plus 40 others who were transported by EMS ambulance, could not be located. Among the 109 women with obstetric conditions for whom paper or electronic hospital records were located, 62 were admitted to hospital L&D services and 4 were admitted to other services, such as 3 to surgery for ectopic pregnancy or post-partum complications. Of all, 40 women were discharged from the ED and 3 left against medical advice. In general, women residing in the United States were older, less likely to be in active labor, and more likely to be discharged home from the hospital ED than Mexican women (P < 0.05).

Fifty-two women among the 62 admitted to L&D services gave birth before discharge, including 36 of the 45 United States residents and 16 of the 17 Mexican residents (Table 4.) According to hospital records, more than one-half of the women had had no prenatal care. Among women who received prenatal care, United States residents were more likely than Mexican residents to have received care in the United States. Most United States residents were either covered by Medicaid (41.7%) or classified as self-pay (36.1%). Most Mexican women were classified as self-pay (56.3%). The proportions of United States and Mexican women who delivered vaginally were similar. Among the vaginal births, 4 were delivered en route (7.7% overall). Other maternal or delivery complications noted were comorbidities in 6 women, postpartum hemorrhage in 3, and breech delivery in 2. Major adverse birth outcomes included 1 stillbirth, 12 preterm live-births ranging from 23 to 36 weeks of gestation (23.1%), 6 live-born infants weighing < 2500 grams (9.6%), and 2 infants with major birth defects.

During a period of 28 months, our analyses indicated that EMS ambulances transported 154 women who had crossed into the United States at an El Paso POE to a hospital for obstetric care. About one-third (52/154) of these women were admitted directly to a hospital and delivered a baby. Most (36/52) of these women reported United States residency; 16 reported residency in Mexico. These 52 births constituted < 0.2% of all births in El Paso County during this time period (19).

The proportion of obstetric emergencies requiring EMS transport from an El Paso POE was more than 10-fold the proportion among women of reproductive age using EMS services in the City of El Paso or in Texas overall. Possible explanations for this finding may include a tendency for POE staff to call EMS when a traveler is in active labor (14), for United States citizens and legal permanent residents living in Mexico to return to the United States to give birth, and for Mexican nationals to enter the United States so that their child will be entitled to citizenship (13). Delivering an infant in the United States automatically confers United States citizenship to the child and might provide access to better care for mother and newborn (13). Infants delivered in Mexico to United States citizens residing in Mexico are eligible for United States citizenship, but the process may be time-consuming and involves additional costs (20).

The population of women crossing the border and giving birth appears to be less likely to have received prenatal care than other women in the border area. A recent study of birth certificates from Mexico and the United States found that 10%–17% of women who reside in the border area of Chihuahua and Texas, respectively, received late or no prenatal care during pregnancy (15); whereas, over one-half of our study population was noted to not have had prenatal care. However, prevalence of prenatal care in the medical record might be underestimated if received in health centers unaffiliated with the hospital of birth (13), or in Mexico. Indeed, our study abstractors noted several instances of reports of pre-natal care received in Mexico or prenatal care records in Spanish that were not recognized in the admissions summary of the hospital record. Prevalence of prenatal care might also be low due to lack of insurance (13). The proportion of births to United States residents enrolled in Medicaid (41.7%) appears lower than the percent among all births in Texas in 2011 (56.4%) (21), and few United States residents had private insurance. Lack of prenatal care in this EMS population may reflect a local population that is poor, relative to Texas overall (22), and that resides part-time in Mexico because of its lower cost of living (6).

Over 60% of study women for whom hospital records were located were admitted to the hospital directly from the ED. This proportion is 2–3 times higher than those reported for general EMS transports in other studies (23, 24), and suggests that EMS assistance was justified. Further evidence of the need for urgent obstetric care is indicated by the nearly 8% of deliveries that occurred in transit, which greatly exceeds the incidence of unintended out-of-hospital deliveries reported in other developed countries, which range from 0.1%–2% (25). Anecdotal reports of birth at POEs are consistent with this finding, such as an adolescent United States resident who recently gave birth prematurely in a POE inspection area while awaiting an ambulance (26). Such deliveries also signal that women may be waiting too long to request EMS assistance. Preterm labor was common in this population, resulting in preterm birth among 23.1% of women as compared to 12.2% and 6.2% of births among Hispanic United States residents and Mexican women, respectively, living on either side of the border area (15). The prevalence of low birth weight also appears high in comparison to births among Hispanic United States and Mexican women in the area (15).

In addition to demonstrating the need for EMS transport, the complications among this study population indicate a need for postpartum care and continued follow-up. Although many women were discharged from L&D with instructions to obtain follow-up from their private physician, lack of insurance coverage among many of these transborder women may make it difficult. Notes in the discharge summaries of patient records from the one public hospital in our study acknowledged this difficulty by frequently advising women to make a postnatal appointment, but at the same time warning that access to the clinic cannot be guaranteed. The extent to which women in the study population do obtain postnatal follow-up is unknown.

Hospital records were missing for 45/154 (29%) women with obstetric emergencies. This proportion is consistent with that of an earlier study of missing hospital records (27), which concluded that records for medically-complicated births were less likely to be found in retrospective record ascertainment. In a recent study of missing clinical information from primary care clinics in Colorado (United States), new patients, recent immigrants, and patients who had multiple medical problems had a higher probability of incomplete clinic records than other patients (28). The absence of hospital records for patients with obstetric emergencies in our study makes the delivery of care after discharge more difficult. This is particularly true for women who return to Mexico following their hospital stays.