Of 2403 cord blood samples collected at the intervention and the control sites, 923 were positive for HIV antibodies in the laboratory and tested for NVP. The sample from 1 woman was excluded from analysis because she was receiving a non-NVP-containing ART regimen. Of the remaining 922 HIV-positive samples, 689 (75%) had detectable NVP levels. NVP coverage was significantly higher (80% = 369 NVP positive/459 HIV positive) at intervention sites compared with 69% (320 of 463) at control sites (RR = 1.16; confidence interval: 1.08 to 1.25; P < 0.0001). Logistic regression in the primary analysis controlling for type of site (urban hospital, rural hospital, and rural health center) found no significant differences (data not shown).
There were 141 HIV positive cord blood results (15% of total positive samples) in women who were not known to be HIV positive on arrival in maternity. NVP was detected in 56% of these women (32 of 57) in intervention sites compared with only 23% of women (19 of 84) in control sites (Table 2).
The cord blood samples from 15 of the 813 women identified as HIV positive at enrollment were HIV negative on retesting. They were excluded from the primary analysis but included in secondary analysis because the staff performance was based on assumed HIV status. These may represent false-positive results from ANC or specimen labeling error either in the ANC or maternity. NVP was detected in 9 of these 15 specimens.
Women Identified as HIV Positive on Arrival at Maternity
Of 813 women identified as HIV positive on arrival at maternity, 206 (25%) were on ART, 419 (52%) said they had swallowed their NVP prophylaxis at home, and 188 (23%) indicated that they had not taken their NVP. Control sites reported more women on ART (29% vs. 22%; P = 0.02) and more women receiving prophylaxis who reported taking their NVP dose before arrival (76% vs. 64%; P = 0.0001) compared with intervention sites. However, this was not associated with an increased proportion of women with NVP detected in cord blood (Table 2).
Cord blood analysis was available for 796 of 813 women identified as HIV positive on arrival (17 were missing cord blood samples). There were no differences between intervention and control sites in the rate of NVP detected in cord bloods of women receiving ART (92% vs. 88%; P = 0.30) or women with known positive status who were not on ART (81% vs. 75%; P = 0.08) (Table 2). Women who reported not taking NVP at home were just as likely to have NVP in their cord blood as those who reported taking it before arrival due to NVP dosing in maternity.
Women Who Previously Tested in ANC and Identified as HIV Negative on Arrival at Maternity
According to maternity registers, 2144 HIV-negative women (including nonenrolled women) arrived at study maternity units during the study period. Significantly more HIV-negative women were retested at intervention sites, 45% (528 of 1185), compared with only 14% (135 of 959) at control sites (RR = 3.17; 95% confidence interval: 2.67 to 3.74; P < 0.0001). For enrolled women who tested HIV negative in ANC, 1377 cord blood results were available, representing a total of 388 person-years of observation. Fifty-eight women had HIV antibody positive results, giving a cumulative incidence of seroconversion during pregnancy of 4% in this population, with an incidence rate of 16.8 new infections per 100 person-years. NVP prophylaxis was detected in 54% (13 of 24) of these newly identified positive women in intervention sites compared with only 26% (9 of 34) of women in control sites (P = 0.03) (Table 2).
Women Arriving at Maternity With Unknown HIV Status
Using register data, the proportion of all women arriving in maternity with unknown status who were tested in intervention sites was 96% (153 of 159) compared with 65% (102 of 156) in control sites (P < 0.0001). Although rates of HIV infection in enrolled women with previously unknown status were similar in intervention and control sites (35% and 42%, respectively), uptake of NVP prophylaxis nearly tripled in intervention sites (Table 2). Of 33 newly identified HIV-positive women in intervention sites, 19 (58%) had NVP detected in cord blood as compared with only 10 of 50 (20%) in control sites (P = 0.0004) (Fig. 2).
NVP Prophylaxis for Women of Unknown HIV Status
Only 1 woman in the intervention sites refused HIV testing in maternity and remained with unknown status. She was offered and accepted sdNVP.
This study demonstrates that a targeted 1-day training intervention for maternity nurses had significant impact on the number of HIV-positive women who received ARV prophylaxis through improved PMTCT service delivery in Swaziland. The intervention significantly increased NVP coverage in HIV antibody-positive cord blood specimens. Participating midwives, who had all previously received the Swaziland national PMTCT training, reported that the targeted training vastly improved their skills and confidence. The study intervention improved adherence to the delivery portion of the overall PMTCT cascade by addressing potential missed opportunities for prevention in maternity.
That 15% of the total HIV-positive cord blood samples were from women not known to be HIV positive on arrival in maternity clearly shows the importance of strengthening PMTCT services at maternity if countries are to reach elimination of mother-to-child transmission. These additional infections can be attributed to those women who arrived with unknown status and were positive (the largest contribution), to those with a previously HIV negative test who had either seroconverted or become newly infected, or to those who had an incorrect test result from ANC or maternity due to specimen mix-up or laboratory error. Ensuring all women receive HIV testing before delivery must be a priority to identify HIV-exposed infants who need postpartum prophylaxis and women who need HIV care.
In intervention sites, women who did not take their labor dose before arrival in maternity were just as likely to have NVP in cord blood as those who did, showing the value of working with maternity staff to improve their skills, both technical and counseling.
The study intervention was not able to document increased reliability of self-reported NVP intake. Other studies have also shown variation in the concordance of NVP presence in cord blood with women's self-reported NVP ingestion.14,15
Despite the relatively high utilization of ART among pregnant women in Swaziland and given the importance of ART for eligible pregnant women and the half-life of NVP, it is concerning that only 89% of pregnant women on NVP-containing ART regimens had detectable NVP levels in cord blood.
Only 1 woman refused HIV testing in maternity, suggesting that offering sdNVP to women of unknown status would have limited value in settings such as Swaziland with high HIV testing rates.
This study has several strengths including the large number of women, different types of facilities studied, and high rates of data and specimen collection. Although 19% of women in the maternities were not enrolled in the study, data on all women were examined from maternity registers (some included here) with no major differences identified in those enrolled and not enrolled. There were no exclusion criteria for enrollment, and the opportunities to “choose” enrollees were extremely limited in both intervention and control sites; thus, it is unlikely that there was a conscious choice of which clients to enroll that would have altered the conclusions of the study. Women who were not enrolled in the study likely still benefited from the enhanced care that resulted from the training at the intervention sites.
There are some limitations to this study. The determination of seroconversion was based on the date and result of a previous HIV negative test recorded on the woman's health card, but the original result was not directly verified. There is a possibility that some women who were actually HIV positive were misclassified as HIV negative on arrival and were subsequently counted as women who seroconverted. Some women whose records show NVP provision in maternity had none detected in their cord blood. Data on the length of time between ingestion of NVP and the delivery of the infant were not recorded; thus, the NVP may have been ingested too close to delivery for detection using the study assay or it was not actually ingested. This limitation applies to both the control and intervention sites, so would not have affected the statistical significance of study findings, but could have lowered the overall rate of NVP coverage reported.
HIV testing is an essential step in PMTCT and is an indicator by which PMTCT program quality is often measured. Focused training of maternity midwives led to significant increases (P < 0.0001) in HIV testing among women who had tested HIV negative ≥3 months before and also among women who had never tested. Twice as many new infections were detected in intervention sites, allowing women and their infants to receive ARV prophylaxis and appropriate follow-on care. Maternity wards remain the last opportunity to establish the presence of HIV before delivery and provide access to critical PMTCT interventions for mother and baby. Recent World Health Organization recommendations that include prophylaxis to prevent HIV transmission through breastfeeding16 makes identification of HIV infection in maternity even more valuable.
The importance of retesting HIV-negative women in high prevalence settings is underscored by the high levels of new HIV infections found in late pregnancy in this study, which are consistent with seroconversion rates of 5%-10% reported from South Africa17 and from 2008 to 2009 in Swaziland.18 Women who seroconvert during pregnancy have acute or recent infection with higher viral loads, with transmission rates to infants reported as high as 67%.19 Detection of incident HIV infections is often delayed or missed due to the window period for rapid tests; however, a large proportion of incident infections during late pregnancy go undetected not because of the limits of technology but due to lack of attention. Based on these results, Swaziland has incorporated third trimester, maternity, and postnatal retesting into its 2010 guidelines.
The level of seroconversion during pregnancy in Swaziland and other HIV prevalence countries is alarmingly high, despite excellent HIV testing coverage and uptake of ARV prophylaxis among HIV-positive pregnant women in ANC. This suggests that programs are giving significant attention to women who test positive in ANC but that women who test negative are not receiving adequate assistance to stay negative. Few health workers understand the increased risk of HIV infection during pregnancy20 and therefore do not provide crucial prevention interventions. Creative strategies that include partner testing and address behavioral issues are needed to keep HIV-negative women from becoming infected during pregnancy and breastfeeding. HIV exposure is ongoing for many women, and the increased vulnerability of pregnant women to HIV needs to be urgently addressed in PMTCT, prevention, ART, and community-based programs.
The results of this study show benefit in reducing missed opportunities to reach women at maternity and taking advantage of this last chance to intervene before delivery. Widespread implementation of the simple inexpensive training program evaluated in this study can significantly increase identification of women with HIV infection and decrease the number of HIV-infected infants.
The successful implementation of the study would not have been possible without the dedication of EGPAF research assistants Edward Groening, Noluthando Bokwe, Mfanimpela Hlatshwako, and Dumisile Simelane. The authors particularly thank Rejoice Nkambule, Deputy Director for Public Health, for her leadership and support of this study; Allison Spensley and Jennifer Ballard Dwan for early work on the protocol; and Laura Guay who provided valuable review and comments for this article. M. P. Kieffer contributed to design, implementation, and analysis and was the primary writer. B. Nhlabatsi and C. M. Wilfert contributed to design and implementation. M. Mahdi and K. Kudiabor contributed to design, implementation, and analysis. H. J. Hoffman provided statistical analysis.
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Keywords:© 2011 Lippincott Williams & Wilkins, Inc.
HIV; mother-to-child transmission; PMTCT; seroincidence; pregnancy; Swaziland