Do you know anybody who sat in jacuzzi around 4 weeks pregnant and still had a healthy baby? i read there's a risk if spina bifida, i'm really scared

Yes - general rule: Spina bifida is a congenital defect known as a neural tube defect (rate is 3.5 per 10,000 births). There are several risk factors: older age, folic acid deficiency, obesity, some medications and hyperthermia during early pregnancy. The latter is generally associated with a febrile illness. At 4 weeks of gestation, the neural tube has not formed and limited exposure is not likely to affect the baby