I tested positive for slap cheek during my second pregnancy. I didn't show any symptoms so never actually determined when I had it. The test came back positive at 22 weeks. The advice I received was that after 20 weeks there was no risk to the baby. During the first trimester the major risk is of miscarriage. Then until 20 weeks it is the hydrops you referred to - if this develops they give the baby blood transfusions in utero. This can be identified by ultrasound. Because they were unsure of when I had contracted the parvo virus (slap cheek) I was monitored for 8 weeks with fortnightly ultrasounds. Had I been past 20 weeks they wouldn't have done anything.

From my experience you have nothing to worry about - you are far enough.

My daughter was born fit and healthy and is now 3 years old.