Alloimmune thrombocytopenia (AIT) or neonatal alloimmune thrombocytopenia (NAIT) is caused by maternal-fetal platelet antigen disparity. If maternal alloimmunization is stimulated, then transplacental antiplatelet IgG antibodies cause severe fetal thrombocytopenia and severe bleeding (Winkelhorst, 2017). his is considered in detail in Chapter 15 (p. 307).
Maternal platelet function and destruction can be severely afected in women with severe preeclampsia. That said, fetal or neonatal thrombocytopenia is rarely caused by the preeclampsia syndrome even when the mother has severe thrombocytopenia. Findings from the large study of mother-infant pairs delivered at Parland Hospital dispelled earlier reports of an association of neonatal thrombocytopenia with preeclampsia (Pritchard, 1987). Instead, neonatal thrombocytopenia was found to be associated with preterm delivery and its numerous complications (Chap. 34, p. 636).
Birth injuries can potentially complicate any delivery. hus, although some are more likely associated with operative delivery by forceps or vacuum, others are seen with otherwise uncomplicated vaginal or cesarean delivery. In this section, some injuries are discussed in general, but specific injuries are
Diseases and Injuries of the Term Newborn 627
TABLE 33-4. Incidence of Major and Minor Birth Trauma-Nova Scotia, 1988-2001
Type of Delivery Birth Trauma
Spontaneous (14) 88,324 1.2
Vacuum (71) 3175 3.7 67
Forceps (58) 10,478 5.2 53
Vacuum (1n05) 609 8.3 100
Forceps (56) 714 7.0 50
Cesarean (8.6) 16,132 OJ 8.3
Labor (12) 10)31 0.4 11.9
No labor (1.2) 5401 0.2 1.1
All (19.5) 119,432 1.6 18 aMajor trauma = depressed skull fracture, intracranial hemorrhage, brachial plexopathy, or combination.
bMinor trauma = linear skull fracture, other fractures, facial palsy, cephalohematoma, or combination.
Data from Baskett, 2007.
described elsewhere in connection with their associated obstetrical complications.
In three population studies that included more than 8 million term newborns, the overall incidence of birth trauma was 20 to 26 per 1000 deliveries (Baskett, 2007; Linder, 2012; Moczygemba, 2010). Data from Nova Scotia show an overall trauma risk of 19.5 per 1000 deliveries (Table 33-4). Only 1.6 cases of major trauma per 1000 were found, and these rates were highest with failed forceps or vacuum delivery and lowest with cesarean delivery without labor. hus, most traumatic injuries were minor, and these had an incidence of 18 per 1000 deliveries.
Trauma associated with cesarean delivery from a vIaternalFetal Medicine Units Network study was described by Alexander and coworkers (2006). There were 400 injuries identiied from a total of 37,100 operations-a rate of 11 per 1000 cesarean deliveries. Although skin lacerations predominated-7 per 1000-more serious injuries in these 400 infants included 88 cephalohematomas, 11 clavicular fractures, 11 facial nerve palsies, nine brachial plexopathies, and six skull fractures.