Surveillance and Treatment to Prevent Fetal Atrioventricular Block Likely to Occur Quickly (STOP BLOQ)

Fetal complete (i.e., third degree, 3°) atrioventricular block (AVB), identified in the 2nd trimester of pregnancy in an otherwise normally developing heart, is almost universally associated with maternal anti-Ro autoantibodies and results in death in a fifth of cases. To date treatment of 3° AVB has been ineffective in restoring normal rhythm (NR) which may be because current surveillance is limited to once- weekly fetal echocardiograms. It is hypothesized that there may be a vital transition period of several hours in which incomplete block (2° AVB) may be successfully treated avoiding fully advanced irreversible 3° AVB. To optimize the likelihood of timely detection of the transition period this study comprises three steps: 1) to risk stratify for high titer anti-Ro antibodies, which are necessary but not sufficient to develop fetal AVB; 2) to empower mothers to identify 2° AVB by using fetal heart rate and rhythm monitoring (FHRM) at home, and 3) to rapidly treat mothers who detect an abnormality by monitoring with an urgent echocardiogram that confirms 2° AVB with the hope of reversing 2° AVB before it becomes permanent (3° AVB). In addition, it will be determined if FHRM reduces the need for weekly echoes. Although mothers with low titer anti-Ro will not be continued in Step 2 and therefore not followed by FHRM, birth ECGs will be collected to confirm that low titer antibodies do not confer risk. It is anticipated that this study will provide an evidenced based surveillance strategy for those mothers at high risk of having a child with 3° AVB.

Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Be <18 weeks pregnant at the time of enrollment
4. Titer of anti-Ro 52 or 60 antibodies ≥1,000 EU
5. Any positive titer of anti-Ro if a history of a previously affected child
6. Ability to take oral medication and be willing to adhere to the dexamethasone and IVIG protocols.
7. Ability to perform Doppler fetal heart rate and rhythm monitoring in the ambulatory setting,
8. Ability to send an audiotext message by cell phone therefore the participant will be informed that they need a phone with texting capabilities. Located within 6 hours drive of the participating pediatric cardiology site
9. Be ≥18 years of age

Exclusion Criteria:

1. Multi-fetal pregnancy
2. Known allergic reactions to components of IVIG, or dexamethasone or maternal IgA deficiency
3. Fetal conduction system disease already present in the current pregnancy
4. Any women who in the opinion of the investigator cannot understand the consent form or be able to perform thrice daily home monitoring or recognize an abnormal fetal heart rate or rhythm
5. Women prisoners
6. Treatment with >20 mg/prednisone q day or with any dose of fluorinated steroids at enrollment