Elevated inhibin levels

I am 20 weeks and my anatomy scan was all good...My first quad screening was normal and panaroma rest was all low risk...second quad came all good for all the other risks...however the doc informed me that one of my hormones..INHIBIN is slightly higher than expected...it is 3.2 and dont know what it is supposed to be..She wants me to get monthly scans to make sure the blood flow is all good tk the uterus...Did anyone go through this and anyone has any idea...Really nervous...Any inputs will help at this time!!