Hot water bottle safe?

Have been getting sore pains in stomach today, think growing pains of baby but I feel miserable. have been using hot water btl and it's comforting but is it safe to use? But worried I could have caused harm. Haven't put it directly on skin over tshirt and fleece jumper!

I got period like cramps during my pregnancy & used to use a heat patch on my lower back. However my doctor told me it's better not to apply heat to the tummy or lower back area so I stopped using them. Was gutted as found the heat really helped with the pain!

I expected that reply but hoped I wouldn't get that! Ye heat always helps me, I would normally stay away from tablets if I can help it! Thanks though