Table 4.

Viral Resistance According to Treatment Group.^*

Mutation	Overall	Zidovudine	Zidovudine plus Nevirapine	Zidovudine plus Nelfinavir and Lamivudine	P Value†
no. of infants/total no. (%)
NRTI-associated mutations
In utero	2/79 (2.5)	0/32	0/23	2/24 (8.3)	0.17
Intrapartum	1/41 (2.4)	0/21	1/10 (10.0)	0/10	0.49
Overall	3/120 (2.5)	0/53	1/33 (3.0)	2/34 (5.9)	0.17
PI-associated mutations
In utero	2/79 (2.5)	0/32	0/23	2/24 (8.3)	0.17
Intrapartum	0/41	0/21	0/10	0/10	—
Overall	2/120 (1.7)	0/53	0/33	2/34 (5.9)	0.15
NNRTI-associated mutations
In utero	9/79 (11.4)	2/32 (6.2)	5/23 (21.7)	2/24 (8.3)	0.19
Intrapartum	3/41 (7.3)	1/21 (4.8)	1/10 (10.0)	1/10 (10.0)	1.00
Overall	12/120 (10.0)	3/53 (5.7)	6/33 (18.2)	3/34 (8.8)	0.15
Any mutations associated with PIs, NNRTIs, or NRTIs
In utero	10/79 (12.7)	2/32 (6.2)	5/23 (21.7)	3/24 (12.5)	0.20
Intrapartum	4/41 (9.8)	1/21 (4.8)	2/10 (20.0)	1/10 (10.0)	0.53
Overall	14/120 (11.7)	3/53 (5.7)	7/33 (21.2)	4/34 (11.8)	0.09

^*Although 140 infants had HIV-1 infection, 20 did not have results from the ViroSeq assay owing to missing specimens or failure of the assay (i.e., the viral load was too low for amplification). The following mutations were considered clinically significant for resistance: D67G, L210W, T215S, K219E, D67 N, T215Y, K65R, K70R, and K219R for nucleoside analogue reverse-transcriptase inhibitors (NRTIs); L10I, D30 N, A71V, and N88D for protease inhibitors (PIs); and Y181C, K103 N, V179E, E138K, V106A, V106 M, V181I, A98G, and V179D for nonnucleoside reverse-transcriptase inhibitors (NNRTIs). Some infants had more than one mutation.

^† P values, which were calculated with the use of Fisher’s exact test, are for multiple comparisons.