Do I need to take bath if my baby boy urinated on me?

You need to thoroughly wash the contaminated area with water.

You do not need to perform ghusl or wudu just because of this.

The matters which invalidate wudu are mentioned here. While ghusl is required when one of the following occurs:

• Secretion of sexual fluids from the private part
• Menstruation and post-natal bleeding
• Entering of the private parts into one another
• Death
• Converstion to Islam

There is an opinion in some madhabs where the urine of a male baby can just be sprinked over with water rather than properly washed, however this is applicable when he does not eat food.

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Reference:

touching najaasah does not invalidate wudoo’

^{— IslamQA also see here here}

I think you need to make wudoo' if the urine gets onto your body (not only clothes), it doesn't matter if the urine is from a baby or someone else or yourself since it would be an impurity (najaasah). If it is only on your clothes, then you can clean the area with water and make wudoo' just in case. Be aware that this is just my interpretation/opinion, Allah knows best. For further information, please have a look here: https://islamqa.info/en/answers/12720/what-should-he-do-if-he-gets-urine-on-his-clothes