Prompted by another post I’ve just seen on here about Rh- in pregnancy and just wanted to share an odd experience I’ve had during my second pregnancy in case anyone else finds themself in a similar situation in the future.
I was surprised not to find anything on Mumsnet and not much in a google search either when I was trying to learn more, (especially not related to second pregnancies), so I thought I would share my experience in case it comes in useful to someone else one day.
To start with, I have Rh+ blood (O+ to be exact). My husband is also O+ and so our daughter is also O+. I am currently pregnant with our second baby. Imagine my surprise when I received a letter after my booking bloods inviting me to have a 28 week anti-D vaccination. I was certain it was a mistake and contacted the midwifery team who were also confused. I was given another blood test which came back to say that although O+ I am something called Partial D, and so I have to be treated as if I’m O- as a blood recipient.
The invitation to the anti-D vaccine wasn’t a mistake as this blood phenotype means it’s possible to develop anti-bodies to the parts of the D antigen that are missing if exposed to RH+ blood, despite presenting as a Rh+ blood group myself. The most information I could find about this was on a website called Blood Bank Guy if anyone fancies some more explanation/ bedtime reading. Essentially there are different types of D variance, including the partial D phenotype as well as something known as weak D.
It is fairly unusual (the midwifery team I’m seeing had never heard of it) but nothing ‘abnormal’, hence why I couldn’t find out much initially. My first concern was obviously that this wasn’t picked up in my first pregnancy with my O+ daughter so I was worried I may have developed the antibodies if I’d experienced a “sensitising event”/ blood transfer with my daughter, which could cause rhesus disease with my current pregnancy.
Thankfully I got lucky, and there were no antibodies present. So at 28 weeks I got the anti-D vaccine and will have the second after the baby arrives. All thankfully a very happy outcome for us.
In terms of why this wasn’t picked up before, I am told that different labs use different reagents to test blood grouping, so it’s likely whatever reagents were used before didn’t show up the partial D phenotype (daughter was born under a different NHS trust so I believe that is likely the case).