Can a power of attorney be used to gain custody

[frogger44]

My husband is going out to sea and I have been given a power of attorney from him. Lateley, things have not been going well in the marriage and he has been threatening to take custody of our child. Is there any way that this power of attorney can be used to gain at least primary custody if not FULL custody of our child? Please, someone write back to me and let me know. I never had a power of attorney before. Thank you.