I must appreciate your awareness about your Disease.
I would like to re-assure you that one -sided pelvic dilatation during pregnancy
is extremely common & less common is bilateral one.& is caused by pressure of pregnant Uterus
over urinary bladder
& disappears after delivery.
Precaution to be taken to prevent UTI by maintaining adequate fluid intake,good hygiene,resting mostly on sides rather than on your back.
Lastly,just to again assure you that 'Hereditary Elliptocytosis' is certainly not the cause of Pelvic dilatation