Laboratory reference intervals during pregnancy, delivery and the early postpartum period.
BACKGROUND
Physiological changes during pregnancy may affect laboratory parameters. Reference values based on samples from non-pregnant women are not necessarily useful for clinical decisions during pregnancy. There is a need to establish reference values during pregnancy in order to recognize pathological conditions.


METHODS
Eight hundred and one women with expected normal pregnancies were included in the study. Of these, 391 had no complications during pregnancy, delivery, or the early postpartum period. Blood samples were obtained at gestational weeks 13-20, 21-28, 29-34, 35-42, at labor, and 1 and 2 days postpartum. Reference intervals were calculated for 36 tests as recommended by the International Federation of Clinical Chemistry and Laboratory Medicine.


RESULTS
Many tests showed such large variations indicating that gestational age-specific reference intervals were necessary. Other tests had different but stable values when compared to non-pregnant women. A minor decrease in albumin levels was observed. This was not only due to pregnancy-associated hemodilution, since other components with the same or a larger molecular diameter did not show a similar decrease. Many tests exhibited a broad distribution around vaginal delivery and in the early postpartum period.


CONCLUSIONS
Only a few parameters were unaffected during uncomplicated pregnancy, delivery, and the early postpartum period suggesting that implementation of gestational age-specific reference intervals is necessary.
Klajnbard
Anna
A
Department of Obstetrics and Gynecology, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark.
Szecsi
Pal B
PB
Colov
Nina P
NP
Andersen
Malene R
MR
Jørgensen
Maja
M
Bjørngaard
Brian
B
Barfoed
Anne
A
Haahr
Katrine
K
Stender
Steen
S
D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis / Q000592:standards; D036861:Delivery, Obstetric; D005260:Female; D005865:Gestational Age; D006801:Humans; D049590:Postpartum Period; D011247:Pregnancy / Q000097:blood* / Q000502:physiology; D011264:Pregnancy Trimesters; D012016:Reference Values; D012709:Serum Albumin / Q000378:metabolism; D013223:Statistics as Topic; D013997:Time Factors
D015415:Biomarkers; D012709:Serum Albumin