Ask an Expert – From Only Child to Oldest Child: Helping Firstborns Adjust to a New Sibling

By: Christina Pay, Utah State University Extension associate professor, Christina.Pay@usu.edu

Firstborn children have a unique role in the family after enjoying the undivided attention of their parents. The birth of a sibling may feel like a loss of this status to them and could trigger feelings of insecurity or rivalry. Studies show that children often exhibit behavioral changes within the first six months after the arrival of a sibling. Behaviors can include tantrums, regression of any type, sleep disruptions, and anxiety. While these behaviors can be challenging for parents, they are developmentally typical responses to changes around them. The quality of the parent’s response can play a critical buffering role. Consider these tips: 

• Prepare the Child – Preparing children during pregnancy can ease the transition. A 2018 study found that firstborns who were informed early about the baby and had time to adjust exhibited fewer behavioral problems and greater emotional readiness. Picture books, role-playing with dolls, and showing ultrasound images can make the experience more concrete for young children. It is helpful to emphasize that love in a family grows rather than divides.
• Maintain Routines and Consistency – Daily rituals such as bedtime routines, special songs, or meal schedules can be powerful anchors for a child during this transition. When daily life feels predictable, children tend to feel safer and more emotionally regulated.
• Encourage Involvement and Helper Roles – Involving the firstborn in age-appropriate caregiving tasks, such as picking out clothes or singing to the baby, can reduce jealousy and feelings of exclusion and help build connection. When the invitation is framed as an opportunity rather than a responsibility, children tend to respond more positively.
• Set Aside Dedicated One-on-One Time – Daily moments of undivided attention, even 10 to 15 minutes of play or reading, can help reassure the firstborn of their continued importance in the family. Labeling this as “our special time” gives it emotional importance. Research confirms that these moments help strengthen emotional resilience and reduce rivalry.
• Validate Emotions and Avoid Shame – It is natural for a firstborn to feel upset or angry. Acknowledging and labeling these feelings, such as saying “It is okay to miss having Mommy all to yourself,” or “It’s hard when Mommy is feeding the baby and you want to play,” helps children feel seen and builds emotional vocabulary. Avoid scolding the child or using any other shame-based responses, as these can compound feelings of distress.
• Monitor and Support Behavior – Regression or misbehavior is common and often signals a need for connection. Rather than discipline, offer comfort, connection, and praise for positive behaviors. Studies show that being attuned to a child’s internal experience buffers against sibling conflict and long-term behavioral concerns. Reinforce that love and attention are not conditional.

The adjustment period to a new sibling varies by child and could take weeks or months. However, when caregivers are warm, consistent, and emotionally attuned, firstborns are more likely to develop a positive bond with their new sibling over time.

Building a strong bond with both children and showing the firstborn how to treat the new baby with kindness helps create a home where everyone feels safe and connected. With a little preparation and ongoing support, most firstborns not only adjust to having a new sibling, but they also grow to love and take pride in their role as the big brother or sister.

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Additional Resources

Zero to Three https://www.zerotothree.orgOffers expert guidance on early childhood development, including sibling transitions.

HealthyChildren.org https://www.healthychildren.org

Parenting advice from pediatricians on introducing a new sibling and managing behavioral changes.

PBS Kids for Parents https://www.pbs.org/parents                                                               

Family routines, emotional support tips, and book recommendations for preparing siblings.

Parenting Science https://parentingscience.com
Evidence-based parenting articles, including research on sibling rivalry and bonding.

Child Mind Institute https://childmind.org
Mental health resources for families navigating big changes, including the arrival of a new baby.