Trial Outcomes & Findings for A Follow-up Study to Describe the Safety of Study Participants Who Received RSVPreF3 Maternal Vaccination (Any Dose) or Controls From Previous RSV MAT Studies During Any Pregnancy Conceived Post Vaccination/Control (NCT NCT05705440)

A total of 3855 participants (3398 maternal participants and 457 infants) completed the informed consent process, of which 475 maternal participants with pregnancy conceived within and beyond 2 years post-vaccination in prior RSV MAT studies and 438 infants born those maternal participants with post-birth data available were included in the current study's Maternal Full Analysis Set (FAS) and Infant FAS respectively.

Of the 475 maternal participants included in the Maternal FAS, only those maternal participants who conceived within 2 years post-vaccination in prior RSV MAT studies (448) and 411 infants born to these maternal participants were considered for all analyses in this study.

A Follow-up Study to Describe the Safety of Study Participants Who Received RSVPreF3 Maternal Vaccination (Any Dose) or Controls From Previous RSV MAT Studies During Any Pregnancy Conceived Post Vaccination/Control

Assessed pregnancy outcomes were live infant with no apparent congenital anomaly; spontaneous abortion with no apparent congenital anomaly; ectopic pregnancy; elective termination with no apparent congenital anomaly; live infant with congenital anomaly, and stillbirth with congenital anomaly. Due to the character limit, further description is added here instead of Analysis population description field: 1 participant in the Control group - Mother was excluded from this outcome's analysis as the gestational age was not provided and hence conception date, which is required for this outcome measure, could not be calculated.

Assessed pregnancy-related AESIs were chorioamnionitis, fetal growth restriction, gestational diabetes mellitus, gestational hypertension, pre-eclampsia, pre-eclampsia with severe features including eclampsia, premature preterm ruptures of membranes, preterm labor and provider-initiated preterm birth. Due to the character limit, further description is added here instead of Analysis population description field: 1 participant in the Control group - Mother was excluded from this outcome's analysis as the gestational age was not provided and hence conception date, which is required for this outcome measure, could not be calculated.

Assessed AESIs were congenital anomalies with internal structural defects, congenital anomalies with major external structural defects, low birth weight \[greater than or equal to (\>=) 1500 grams (G) and below (\<) 2500 G\], very low birth weight (\>=1000 G and \<1500 G), neonatal death in a term live birth (\>=37 weeks of gestational age), preterm birth (\<37 weeks of gestational age) and small for gestational age.

Assessed pregnancy outcomes were live infant with no apparent congenital anomaly; spontaneous abortion with no apparent congenital anomaly; ectopic pregnancy; elective termination with no apparent congenital anomaly; live infant with congenital anomaly; molar pregnancy; stillbirth with congenital anomaly and stillbirth with no apparent congenital anomaly. Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, pregnancy outcomes were calculated based on the number of pregnancies observed from the maternal participants.

Assessed pregnancy-related AESIs were preterm labor, provider-initiated preterm birth, premature preterm rupture of membranes, gestational diabetes mellitus, gestational hypertension, pre-eclampsia with severe features including eclampsia, pre-eclampsia, fetal growth restriction and chorioamnionitis. Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, pregnancy-related AESIs were calculated based on the number of pregnancies observed from the maternal participants.

Assessed AESIs were congenital anomalies with internal structural defects, congenital anomalies with major external structural defects, low birth weight (\>=1500 G and \<2500 G), very low birth weight (\>=1000 G and \<1500 G), neonatal death in a term live birth (\>=37 weeks of gestational age), preterm birth (\<37 weeks of gestational age) and small for gestational age.

The selected risk factors assessed were prior preterm delivery, pregnancy complications, gestational diabetes mellitus, chorioamnionitis during pregnancy, hypertensive disorders of pregnancy, pre-existing hypertension, pre-existing diabetes, vaginal bleeding during pregnancy, polyhydramnios or oligohydramnios during pregnancy and fetal growth restriction. The below presented data is read as follows: Yes = the respective risk factor was experienced by the maternal participant in the past and/or during pregnancy. No = the respective risk factor was not experienced by the maternal participant in the past and/or during pregnancy. With preterm birth event = the assessed pregnancy resulted in a preterm birth event. Without preterm birth event = the assessed pregnancy did not result in a preterm birth event. As pre-specified in the SAP, preterm birth event data stratified by selected risk factors was calculated based on the number of pregnancies observed from the maternal participants.

The age groups at vaccination assessed were \<18 years, 18-24 years, 25-34 years and \>=35 years. Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, preterm birth event data stratified by age group at vaccination was calculated based on the number of pregnancies observed from the maternal participants.

The pre-pregnancy body mass index (BMI) categories assessed were \< 30 kilogram per square meter (kg/m\^2), \>=30 kg/m\^2 and missing (no pre-pregnancy BMI data available). Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, preterm birth event data stratified by pre-pregnancy BMI was calculated based on the number of pregnancies observed from the maternal participants.

The races assessed were American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Other Pacific Islander, White, Multiple, Not reported and Unknown. Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, preterm birth event data stratified by race was calculated based on the number of pregnancies observed from the maternal participants.

The multiple gestation pregnancies assessed were one gestation, two gestations and three gestations. Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, preterm birth event data stratified by multiple gestation pregnancy was calculated based on the number of pregnancies observed from the maternal participants.

The geographic regions assessed were Europe, Australasia, North America, Latin America and Africa. Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, preterm birth event data stratified by geographic region was calculated based on the number of pregnancies observed from the maternal participants.

The economic regions assessed were low and middle-income countries (LMIC) and high-income countries (HIC). Due to the character limit, further description is added here instead of Analysis population description field: As pre-specified in the SAP, preterm birth event data stratified by economic region was calculated based on the number of pregnancies observed from the maternal participants.

The selected risk factors assessed were prior preterm delivery, pregnancy complications, gestational diabetes mellitus, chorioamnionitis during pregnancy, hypertensive disorders of pregnancy, pre-existing hypertension, pre-existing diabetes, vaginal bleeding during pregnancy, polyhydramnios or oligohydramnios during pregnancy and fetal growth restriction. The below presented data is read as follows: Yes = the respective risk factor was experienced by the maternal participant in the past and/or during pregnancy. No = the respective risk factor was not experienced by the maternal participant in the past and/or during pregnancy. With preterm birth event = the assessed pregnancy resulted in a preterm birth event. Without preterm birth event = the assessed pregnancy did not result in a preterm birth event.

The age groups at vaccination assessed were \<18 years, 18-24 years, 25-34 years and \>=35 years.

The pre-pregnancy BMI categories assessed were \< 30 kilogram per square meter (kg/m\^2), \>=30 kg/m\^2 and missing (no pre-pregnancy BMI data available).

The races assessed were American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Other Pacific Islander, White, Multiple, Not reported and Unknown.

The multiple gestation pregnancies assessed were one gestation and two gestations.

The geographic regions assessed were Europe, Australasia, North America, Latin America and Africa.

The economic regions assessed were LMIC and HIC.