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Pregnancy-related group A streptococcal infection

Dennis L Stevens, MD, PhD
Amy Bryant, PhD
Section Editor
Daniel J Sexton, MD
Deputy Editor
Elinor L Baron, MD, DTMH


In the mid-nineteenth century, it was common for clinicians to perform autopsies on women who had died of postpartum infection. In the absence of hand washing between autopsies and deliveries, the clinicians could transmit group A Streptococcus (GAS) to laboring women, leading to postpartum infection [1]. During this time, Semmelweis deduced that physicians transmitted infection via their hands to pregnant women during labor and delivery and showed that hand washing could reduce transmission [2]. A century later, maternal mortality was reduced further with the introduction of antiseptics and penicillin [3].

Invasive group A streptococcal infections reemerged in the mid-1980s [4], including those associated with pregnancy and childbirth [5]. The annual incidence of GAS postpartum infection in the United States is 6 per 100,000 live births [6]. Globally, puerperal sepsis causes approximately 75,000 maternal deaths per year [7], with the highest maternal mortality in Asia (11 percent), Africa (9 percent), and Latin America and the Caribbean (7 percent) [8]. One retrospective review in Israel noted an incidence of 1 postpartum GAS infection per 2837 deliveries [9].

Issues related to pregnancy-related group A streptococcal infections will be reviewed here. Issues related to non-gynecological GAS infections such as empyema, necrotizing fasciitis of extremities, and pyomyositis are discussed separately. (See related topics.)


Pregnant and postpartum women have a 20-fold increase in attack rate for invasive group A streptococcal (GAS) infection compared with nonpregnant women [10]. Among patients with pregnancy-related GAS, approximately 85 percent of infections occur postpartum and 15 percent occur during pregnancy [9,11]. In one study including 67 patients with pregnancy-related GAS, 84 percent followed vaginal delivery, and the majority occurred within the first four days postpartum (73 percent) [11].

Most cases of pregnancy-associated GAS infection are community acquired; approximately 15 to 25 percent of GAS postpartum infections are nosocomially acquired [9,12]. Patients with intrapartum or late postpartum infection are more likely to have had upper respiratory tract GAS infection prior to development of intrauterine infection. Contact with young children during pregnancy represents an underappreciated risk factor for maternal GAS acquisition, since pharyngeal GAS colonization rate is higher in children than adults (25 versus 5 percent). Pharyngeal screening for GAS is appropriate for pregnant women with pharyngitis or upper respiratory illness; this is particularly relevant for women who have close contact with young children.

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Literature review current through: Nov 2017. | This topic last updated: Jul 11, 2017.
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