I am about 5 weeks pregnant. most obgyns only make appointments at 8 or 13 weeks. do i need a check up with a gp or midwife before then? also, can i continue to use the sauna? thanks

Earlier is better: "Making first prenatal appointments at 8 or 13 weeks" is now considered a rather obsolete, outdated and unsafe tradition in most obstetrical centers. The earlier your evaluation by a knowledgeable clinician the better. A "preconception appointment" would have been even better. Seek a consultation with an obstetrical team (doctor, midwife, nutritionist, geneticist...) as soon as you can.