The guarantee letter posted online by the Internet user. [Photo/Orient Today]

Having a second baby not just affects parents. In many cases, the firstborn especially has a hard time dealing with the situation.

An Internet user posted a written guarantee demanded by her daughter that reads: "I promise our firstborn child will come first as my love." The guarantee is to assuage the feeling of insecurity of the daughter, reported Orient Today on Thursday.

According to the parent, their firstborn child worries that they will not love her anymore if they had a second child.

This insecurity seems to be shared by other children, too. Earlier this month, it was reported that a 13-year-old girl threatened her parent to kill herself if they had a second child. Her parents found a blade and scars on her wrist before deciding to terminate the 13 weeks pregnancy.

Read our next story to see what a woman is offering for daughter.