A descriptive study of New Zealand midwives' primary care management of iron status in pregnancy and the postpartum period
Background: Globally there is no consensus on haemoglobin (Hb) parameters that define maternal anaemia. Therefore it is difficult to distinguish physiological anaemia of pregnancy from anaemia associated with pathology. Low maternal iron status is associated with adverse outcomes, although the evidence is difficult to interpret. Non-anaemic iron deficiency requires prevention and treatment, before end stage iron deficiency anaemia. Increases in serum ferritin (SF) secondary to inflammation, gives misleading results of iron stores if not tested with C-reactive protein (CRP). Given the complexities, how do Lead Maternity Carer (LMC) midwives in New Zealand manage anaemia and iron deficiency, without a clinical guideline? Methods: In this descriptive study, quantitative data was retrospectively collected from September-December 2013, from LMC midwives (n=21) and women (n=189), in one New Zealand area. Main outcomes assessed were women’s iron status. Anaemia was defined as Hb <110g/L in the first trimester, <105g/L in subsequent trimesters, and <100g/L postnatally. Iron deficiency was defined as SF <20 μg/L, if CRP<5mg/L. A secondary analysis of iron status and body mass index (BMI) was undertaken. Results: Of the 186 women who had Hb testing at booking, 46% did not have ferritin tested concurrently. Of the 385 ferritin tests undertaken, 86% were not tested with CRP. Despite midwives prescribing iron for 48.7%, and recommending iron for 16.9% of second trimester women, 47.1% had low iron status before birth. Only 22.8% had Hb testing postpartum, including 65.1% (of 38) with blood loss >500mls. Results of a secondary analysis showed a significant difference (p=.05) between third trimester ferritin levels in women with BMI ≥ 25 (Md SF 14 μg/L) and BMI < 25 (Md SF 18 μg/L). Conclusions: Inconsistent testing of ferritin made it difficult to assess maternal iron status, especially without concurrent testing of CRP. Midwives may not understand and recognise the progression from iron sufficiency to end-stage iron deficiency anaemia. Even without further research this small study may indicate the need for improved education for midwives, and a clinical guideline. More complex studies on the prevalence in New Zealand, BMI and iron status, and maternal outcomes especially in the postpartum period, are warranted.