Hi acv1970,
There is not a lot of information about Hb Kokomo (HBB:c.223G>A), but it does appear to be a fairly mild mutation. It's surprising that it was found because the blood indices look normal and not at all like thal minor, so most doctors wouldn't even be looking for any hemoglobin disorder carrier state and only an experienced lab tech would pick up the abnormal hemoglobin in a hemoglobin electrophoresis test. Was this found through a blood test or was a DNA analysis done?
http://globin.bx.psu.edu/cgi-bin/hbvar/query_vars3?mode=output&display_format=page&i=1249
Clinical presentation
hemolytic mild Anemia
Laboratory findings
Hb X 41.8 % of total Hb
Reticulocytes 2.1 - 2.9 %
A hemolytic anemia is one where the red blood cells break down at a faster rate than normal, but this is a mild anemia. The higher than 40% Hb Kokomo of total Hb may have some effects that would be related to the relative oxygen affinity of Hb Kokomo compared to normal hemoglobin, but I don't know if this information is available. An example of this is found with HbF, fetal hemoglobin which has a higher affinity for oxygen than normal hemoglobin. This property actually makes the oxygen in HbF less readily available.
I found one other mention of Hb Kokomo at
http://www.haematologica.org/content/93/9/1380.full?ck=nck#F1Table 1 attached to that article show those with Hb Kokomo as having higher than normal hemoglobin levels, but this was based on only 3 cases because this is quite rare. Have you had any sign of low hemoglobin in your life like low Hb or hematocrit in blood tests? I hope your case will be reported by the hematologist to the PSU database.
The one supplement I recommend to pregnant thal minor women is natural vitamin E. Anytime there is abnormal hemoglobin and hemolysis, there will be more of a chance of clotting between the uterus and placenta, even though it isn't established by any studies, we have observed here that there is a high incidence of miscarriage in thal minor women who report their stories here. Vitamin E is an antioxidant and has mild blood thinning properties, both of which help counter the effects of hemolysis. Good nutrition during pregnancy is key and the other vitamins you're already taking are also recommended.