A Study of Nipocalimab in Pregnancies at Risk for Severe Hemolytic Disease of the Fetus and Newborn (HDFN)

Percentage of pregnancies that did not result in fetal loss, IUT, hydrops fetalis, or neonatal death (during the neonatal period) will be reported. Hydrops fetalis is defined as the presence of greater than or equal to(>=)2 abnormal fluid collections in the fetus or neonate, such as ascites, pleural effusions, pericardial effusion, and generalized skin edema (skin thickness greater (>)5 millimeter [mm]). PMA is the time elapsed between the first day of the last menstrual period and birth (gestational age) plus the time elapsed after birth (chronological age).

Number of participants with HDFN by severity will be reported. The severity of HDFN is defined as: 5 (fatal): fetal or neonatal death due to any reason; 4 (severe): hydrops fetalis (in fetus or newborn) or receiving IUT during pregnancy as a result of HDFN but not 5 (fatal); 3 (moderate): neonatal exchange transfusions received as a result of HDFN related hemolysis and jaundice but not 4 (severe) or 5 (fatal); 2 (mild): neonatal simple transfusions received due to HDFN after birth, with or without phototherapy, but not 3 (moderate), 4 (severe), or 5 (fatal); and 1 (minimal or none): not in 2 (mild), 3 (moderate), 4 (severe), or 5 (fatal) as described above. Here database lock implies the last participant has given birth or terminated their pregnancy, completed the Week 4 visit after delivery, and whose neonate has also completed the Week 4 visit (or 41 weeks PMA, whichever is later) or died prior to this timepoint.

Time to first occurrence of IUT or hydrops fetalis will be reported.

The NMMI will be assessed with the following categories: fatal: fetal/neonatal death; major morbidity: any of intraventricular hemorrhage grade 3/4, seizures, hypoxic-ischemic encephalopathy, necrotizing enterocolitis stage 2/3, respiratory distress syndrome requiring mechanical ventilation, bronchopulmonary dysplasia requiring oxygen support, or persistent pulmonary hypertension; Minor morbidity: anemia requiring simple transfusion, hyperbilirubinemia requiring an exchange transfusion, hypotension requiring treatment, intraventricular hemorrhage grade 1/2, necrotizing enterocolitis stage 1, or respiratory distress syndrome not requiring mechanical ventilation; None: no major or minor morbidities described above. Hyperbilirubinemia requiring phototherapy will be classified in this category'

Number of IUT's received during the pregnancy will be reported.

Percentage of pregnancies with fetal loss will be reported.

Percentage of pregnancies with fetal or neonatal death (through the neonatal period) as a result of HDFN will be reported.

Percentage of pregnancies with hydrops fetalis will be reported. Hydrops fetalis is defined as the presence of >=2 abnormal fluid collections in the fetus or neonate, such as ascites, pleural effusions, pericardial effusion, and generalized skin edema (skin thickness >5 mm).

Percentage of pregnancies receiving IUT during pregnancy will be reported.

GA at first IUT will be reported.

Percentage of pregnancies receiving >1 IUT during pregnancy will be reported.

Percentage of pregnancies receiving IUT or HDFN resulting in fetal demise <GA Week 20 will be reported.

Gestational age at delivery will be reported.

Percentage of pregnancies with neonatal death through the neonatal period will be reported.

Percentage of liveborn neonates with HDFN-related morbidities other than anemia and hyperbilirubinemia or jaundice will be reported.

Absolute weight of liveborn neonates or infants will be reported.

Change from baseline in weight of liveborn neonates or infants will be reported.

Liveborn neonates length of stay in neonatal intensive care unit will be reported.

Percentage of liveborn neonates receiving exchange transfusions for HDFN will be reported.

Number of neonatal exchange transfusions per liveborn neonate will be reported.

Percentage of liveborn neonates or infants with simple transfusions for HDFN through the neonatal period (for the first database lock) or 12 weeks (for the second database lock) after birth will be reported.

Number of simple transfusions for HDFN per liveborn neonate or infant through the neonatal period (for the first database lock) or 12 weeks (for the second database lock) after birth will be reported.

Percentage of liveborn neonates with hyperbilirubinemia treated with phototherapy will be reported.

Number of days of phototherapy received for hyperbilirubinemia per liveborn neonate will be reported.

Percentage of liveborn neonates or infants receiving IVIg for HDFN treatment will be reported.

Number of maternal deaths will be reported.

Number of participants with AEs, serious adverse events, and AEs of special interest (AESIs), AE's leading to discontinuations, infections, serious infections, infusion reactions, and hypersensitivity reactions will be reported. Treatment-emergent adverse events associated with the following situations are considered as AESIs: hypoalbuminemia, clinically significant bleeding with a corresponding placental finding on ultrasound, maternal infections that led to clinically significant morbidities or mortalities in fetus or neonates, Infections that are severe or require intravenous (IV) anti-infective or operative or invasive intervention in maternal participants or neonates or infants, and infants with hypogammaglobulinemia.

Number of maternal pregnancy complications will be reported.

Number of participants with IUT related complications will be reported.

Percentage of pregnancies with cesarean delivery, cesarean delivery due to IUT complications, preterm birth <GA week 28, preterm birth <GA week 32, preterm birth <GA week 34, preterm birth <GA week 37, fetal growth restriction, and preeclampsia will be reported.

Percentage of liveborn neonates or infants who died will be reported.

Percentage of liveborn neonates or infants with AEs, SAEs, AESIs, infections, serious infections will be reported. An AE is any untoward medical occurrence in a clinical study participant administered a pharmaceutical (investigational or non-investigational) product. Any event requiring hospitalization (or prolongation of hospitalization) that occurs during participation in the study must be reported as an SAE.

Percentage of liveborn neonates or infants receiving IVIg for non-HDFN indications will be reported.

Percentage of liveborn neonates or infants with abnormal hearing will be reported.

The Bayley Scales of infant development is considered the standard assessment of early child development and includes cognition, language, motor skills, social emotional, and adaptive behavior will be reported. The Bayley Scales (3rd edition) are reference standards that measure infant and toddler development in five areas: cognition, language, motor skills, social-emotional and adaptive behavior. The cognition, language and motor skills scales are directly administered to the infant, while social-emotional, and adaptive behavior scales are caregiver questionnaires. The scores are standardized using norm reference samples with representative demographics and age adjusted for prematurity. Higher scores in the Bayley Scales indicate better outcomes.

Change from baseline in GAD7 over time during pregnancy and postpartum will be reported. The GAD-7 scale is a self-administered questionnaire designed to measure anxiety. The recall period for all items is the past 2 weeks. Responses to all items are rated on a 4-point Likert scale ranging from 0 "not at all" to 3 "nearly every day". The total score ranges from 0 to 21, with higher scores indicating higher severity of anxiety symptoms.

Change from baseline in SF-36v2 acute form domain score will be reported. The SF-36 version 2 acute is a self-administered, 36-item questionnaire measuring health-related quality of life and includes 8 domains that measure physical functioning, role limitations due to physical health problems, bodily pain, general health, vitality social functioning, role limitations due to emotional problems, and mental health. The 8 domains can be aggregated into 2 summary scales that reflect physical and mental health: a physical component summary and a mental component summary. Responses to all items are rated on a 3, 5, or 6-point Likert scale, with higher scores indicating better health status.

Change from baseline in EQ-5D-5L visual analogue score will be reported. The EQ-5D descriptive system is comprised of 5 items across the following 5 dimensions: mobility, self-care, usual activities, pain or discomfort and anxiety or depression. The EQ-5D-5L uses a 5-point Likert response scale ranging from "no problems" to "extreme problems", with higher scores indicating better quality of life. EQ-5D-5L consists of the EQ-5D descriptive system and the EQ visual analogue scale (EQ-VAS). EQ-VAS score ranges from 0 to 100, where 0 = worst imaginable health state and 100 = best imaginable health state. Higher score indicates good health state.

Change from baseline in EQ-5D index score will be reported. The EQ-5D descriptive system is comprised of 5 items across the following 5 dimensions: mobility, self-care, usual activities, pain or discomfort and anxiety or depression. The EQ-5D-5L descriptive system uses a 5-point Likert response scale ranging from "no problems" to "extreme problems", with higher scores indicating better quality of life.

IQI score for neonate or infant will be reported. The IQI consists of 7 health attributes including sleeping, feeding, breathing, stooling or poo, mood, skin, and interaction. Responses to all items are rated on a 4-point Likert scale, with higher scores indicating better quality of life.