This new approach, called the ��specially-designed multiple imputation�Cbased fuzzy clustering method�� (s-FCM), can be used even when there are missing values. Using inhibitor Pazopanib this method, Fang et al. (2011) detected a graded exposure effect on neonatal birth weight and neurobehavioral outcome in a sample of 361 women in the Midwest Infant Development Study (MIDS, R01 “type”:”entrez-nucleotide”,”attrs”:”text”:”DA014661″,”term_id”:”78308928″DA014661; Espy, PI). The MIDS dataset has four types of exposure data (22 exposure variables, where 9 had missing value rates ranging from 0.6% to 18.3%): self-reported smoking, maternal urine cotinine levels, nicotine by cigarette brand, and nicotine dependence scores.

Using the s-FCM, three subgroups with distinct smoking behavior patterns across pregnancy resulted, which were labeled: nonexposed (NE, N = 172), lighter tobacco-exposed (lTE, N = 140), and heavier tobacco-exposed (hTE, N = 40). Differences in birth weight were observed between the hTE (M = 3,277.7 g) and NE (M = 3,431.6 g) groups but not between the lTE (M = 3,400.3 g) and NE groups. Furthermore, on a standardized neonatal behavioral assessment (Riese, 1982) administered at birth, 2-, and 4 weeks of age, the s-FCM identified differences in the pattern of developmental change in irritable reactivity, again, with significant differences between hTE and NE but not between lTE and NE. The predictive power increased by at least 13% over the nonsignificant comparisons of exposure groups defined by traditional binary cut-score groupings (Espy et al., 2011).

These findings suggest that s-FCM may facilitate the detection of subtle exposure effects on a variety of smoking-related outcomes. To understand whether s-FCM has this utility, we need to test it further on known exposure-related outcomes (e.g., birth weight). Thus, the purpose of the present study is to examine if a similar number of exposure subgroups and a graded exposure effect can again be detected on perinatal growth outcomes by applying the s-FCM method to a study cohort, the Maternal Infant Smoking Study of East Boston (MISSEB, now followed as the East Boston Family Study; Pickett, Kasza, Biesecker, Wright, & Wakschlag, 2009; Wakschlag et al., 2011), with different exposure variables and participant characteristics (Pickett et al., 2008).

Specifically, we hypothesize that as in MIDS, three subgroups will be identified: (a) heavier, (b) lighter, and (c) nonexposed and that these groups, particularly the heavier versus nonexposed groups, will differ in fetal growth outcomes. Since mixed results exist in the literature as to the significance of exposure effects on neonatal Carfilzomib body length and head circumference (e.g., Conter, Cortinovis, Rogari, & Riva, 1995; Espy et al., 2011; Hardy & Mellits, 1972; Nelson, Jodscheit, & Guo, 1999), these effects may differ in MISSEB and MIDS.