Situation: The public health nurse at a Barangay Health Station (BHS) is assessing a newly registered family. The father, 30, is a tricycle driver; the mother, 27, is a homemaker; their only child is a 20-month-old son; and the mother's widowed mother, 62, lives with them. No member has a current illness, and the son's immunizations are complete for his age under the National Immunization Program (NIP). In Duvall's framework, this family remains in its current developmental stage until the son reaches what age?

Duvall stages are set by the age of the oldest child. With a 20-month-old only child, the family is in the childbearing stage, which lasts from the birth of the first child until that child is 30 months (2.5 years) old; the preschool stage then runs until the oldest child is 6. Child-development texts often place the preschool period at 3 to 5 years, which is why 36 months is a common wrong answer for Duvall's family stage.

Understanding Duvall’s Family Developmental Stages

Duvall’s framework organizes family life according to the age of the oldest child, because the oldest child’s developmental needs set the family’s primary tasks and transitions. In this scenario, the only child is 20 months old, which places the family in the childbearing stage—the period from the birth of the first child until that child reaches 30 months (2.5 years). The family remains in the childbearing stage until the son turns 30 months old, not 36 months.

The next stage, the preschool stage, begins when the oldest child is 30 months and continues until the child is 6 years old. Many examinees confuse this with early childhood or preschool definitions used in pediatric growth and development, where the preschool period is often described as 3 to 5 years. Watch out! Duvall’s family stage boundary is 30 months, not 36 months—this is a classic distractor in licensure exams.

Why the Age of the Oldest Child Matters

Family development theory views the family as a unit that moves through predictable transitions. Each stage carries developmental tasks that the family must accomplish to support both individual growth and family stability ^[1]. In the childbearing stage, tasks center on integrating a new infant into the family, adjusting to parenting roles, and maintaining the couple relationship. As the oldest child enters the preschool stage, the family’s focus shifts to socialization, safety, and preparing the child for broader peer and school environments.

The provided evidence reinforces that family life cycle stages are defined by the age of the first child. One study explicitly categorizes working mothers by the age of their first child, using 0–35 months as the earliest family stage before the preschool stage begins ^[3]. This operationalization aligns with Duvall’s cutoff: the childbearing stage ends when the first child is 30 months, and the preschool stage then extends through the remainder of the 0–35 month window into early childhood. The family’s developmental stage is tied to the oldest child’s age because that child’s needs drive the family’s tasks and resources.

Applying This to the Barangay Health Station Visit

For the public health nurse, correctly identifying the family stage guides anticipatory guidance and health teaching. A family with a 20-month-old only child is still navigating the childbearing stage. The nurse should focus on:

Family Stage	Oldest Child’s Age	Key Nursing Focus
Childbearing	Birth to 30 months	Parenting adjustment, infant/toddler nutrition, immunization follow-up, maternal health, couple relationship support
Preschool	30 months to 6 years	Safety, discipline, socialization, school readiness, growth monitoring

Key point! The transition from childbearing to preschool occurs at 30 months of the oldest child’s age. Since the son is 20 months old, the family will remain in the childbearing stage for another 10 months. The correct answer is 30 months, not 24 months, 36 months, or 48 months.

Family development theory also recognizes that individual and family life cycles intertwine ^[1]. In this household, the widowed grandmother at 62 years is in her own later-life stage, and her presence may influence family roles and resources. However, Duvall’s stage classification for the family unit is determined solely by the oldest child’s age, so the grandmother’s age does not change the family’s current developmental stage. A multigenerational household still follows the same family stage sequence based on the oldest child.