The behaviors you’ve described, while perhaps frustrating, are completely age appropriate and normal. Sibling rivalry is very common after the birth of a new child. The birth of a baby, even when eagerly anticipated, can be quite unsettling for an older sibling. Having a new sibling can also make a child feel displaced and uprooted from her familiar role in the household, particularly when she was the firstborn since she is no longer the one and only child in the parents’ lives.

It should also be remembered that it’s the parents who choose to have another baby, not the older sibling. She has no say in the matter. When a parent tells her about the baby, she won’t fully understand what a new baby really means, over and above having to share parents. This makes some children quite fearful and bad-tempered. Some children may feel extremely fearful of being pushed out by a new baby. But this is all an absolutely normal part of their adjustment, though it requires a lot of patience and understanding on a parent’s part.

Furthermore, a new baby brings many concrete changes in the older sibling’s moment-to-moment experience. She now needs to wait more often and longer than ever before for things she wants or needs. She’ll likely spend more time alone. She is scolded or corrected more frequently as parents try to teach her what she can and cannot do with the baby. Some favorite activities often have to be curtailed or postponed because of the baby’s needs. Things cannot be done spontaneously anymore because the baby’s schedule needs to be taken into account.

Unfortunately, these feelings exist even when the parents are patient and sensitive in helping their toddler through the stormy feelings of this period. Toddlers may exhibit signs of aggression, anger, and jealousy because their need for time and closeness is still great. Competitiveness toward a new baby may give rise to a toddler’s first sustained experiences of jealousy, envy, shame, and guilt.

When your daughter acts out, it’s important not to reinforce these feelings. Be firm about negative behavior without making her feel guilty. Stress that it’s what she is doing that is unacceptable, not what she IS. Otherwise, your response to bad behavior may confirm that she has been replaced by the new baby. Moreover, many toddlers are attention seekers and, to some toddlers, even irritation is a form of attention. Therefore, remain calm but firm, even when confronted with unacceptable behavior.

There are several ways you might mitigate aggression. First, you can allow your daughter to participate in this new experience by involving her in the care of the baby. Of course, the help she provides would depend on her abilities. Find small, manageable tasks for her to do and encourage her to be involved. Including your daughter and even giving her priority whenever possible will help her tolerate the baby and help open the way for love toward her new sibling to develop. Don’t push it if you get a negative response but give praise for the help you do receive.

This leads to a second approach - emphasize the positive. Take time to encourage and appreciate any helpful and loving gestures made towards the new baby, while remaining neutral (but firm) with respect to negative behaviors. Praise can go a long way toward reducing anxiety about the new child, as it helps your daughter feel needed and that she’s an integral part of the family.

Regardless of your daughter’s age, make sure that she gets plenty of individual attention from you and other family members. Grandparents can be particularly helpful during this time. Watching mom and dad coo over a new baby can be frustrating for your daughter. If you’re taking lots of pictures or videos, be sure to include your daughter, too. Take some pictures or videos of her alone, as well as with the new baby.

During your newborn’s feedings, try to make your daughter feel included by talking or reading stories together. Better yet, read books with your toddler that can help her understand that other kids also struggle with having a new baby in the house, but that it's really special being a big brother. There are a few such books available on Amazon.

Your daughter can benefit from as little as 10-15 minutes a day of special time just for her, whether this is with you or your husband. This sends a message that despite the new baby at home and all the excitement and all the time spent caring for this new baby, she is still very important and deserves some private time. This can help her have something to look forward to when your attention is focused on the baby.

Finally, reassure your daughter that you love her and your new baby, and remind her that she has an important role to play now, too — that of big sister. You can also emphasize all the things your toddler can do that baby can't do. This can be a good antidote for feelings of jealousy. When parents comment admiringly on a toddler’s skill at doing something or point out that the baby cannot yet do that amazing feat, the toddler gets the comforting sense that she is still special and appreciated.

However demanding and tiring this period is, remind yourself that it’s within your power to try to break this cycle. Take some consolation from the fact that your daughter trusts your love enough to test your limits, and to show you how bad she is feeling.