US immigration authorities understand that in many cases where a petitioner is granted a US visa (such as a K-1 visa), the petitioner will likely want to bring their family with them to the US. In many cases, there are categories of visas which exist specifically to allow the children and spouses of petitioners to enter the US. If you are applying for a US visa to enter the US and want to travel with your spouse and child, you will want to file a separate petition for a US entry visa for your children and spouse.
For example, if you have married a US citizen outside of the US, you can apply for a K-3 visa, which is a US entry visa that allows you to enter the US as a non-immigrant. Once you are in the US on a K-3 visa, you can then apply to adjust to immigrant status. You can then obtain a green card and even eventually apply for US citizenship.
If you have children, you can apply for a K-4 visa for these children so that they can travel to the US with you and stay and study in the US. An alternative to the K-3 Visa is the K-1 visa, which allows immigrants who are engaged to a US citizen to travel to the US in order to get married. With a K-1 visa, there is no need to apply for an adjustment of status, as a conditional green card is issued once the wedding has taken place and the couple have applied for the card. With a K-1 visa, the couple can live and work in the US from the moment the K-1 holder enters the US.
The V visa is another type of US entry visa available to minor children (under the age of 21) and some spouses of US lawful permanent residents. The visa category was created in 2000 to allow families to be reunited during the long US immigration process. However, the USCIS has not been approving such visa applications as the visas were part of a program and applicants needed to file before December 22 2000. Therefore, this entry visa is practically no longer available currently. There have been bills in place to create US entry visa options for immigrants who are going through the US immigration process and have been separated from their families. However, as of 2011, no such bill has been enacted.