Fetal Hypoxia in Diabetic Pregnancy

Kari Teramo, M.D.

Department of Obstetrics and Gynecology, University Central Hospital,

Helsinki, Finland

Jorgen Pedersen: The pregnant diabetic and her newborn, 1977

Frequency (%) of fetal and neonatal complications in Type 1 diabetic

pregnancies and in the general population in Sweden 1991 - 2003 ------------------------------------------------------------------------------------------Outcome variable Type 1 DM Controls Adjusted OR (95% CI)------------------------------------------------------------------------------------------Singleton births 5.089 1.260.207

Stillbirth 1.5 0.3 3.34 (2.46 – 4.55)Neonatal mortality 0.51 0.18 3.05 (1.68 – 5.55)Perinatal mortality 2.0 0.48 3.29 (2.50 – 4.33)

LGA (≥ 2.0 SD) 31.0 3.6 11.40 (10.6 – 12.4) SGA (≤ -2.0 SD) 2.3 2.5 0.71 (0.55 – 0.91)Apgar <7 at 5 min. 3.1 1.1 2.60 (2.14 – 3.17) Erb’s palsy 2.1 0.25 6.69 (4.81 – 9.31) RDS 1.0 0.2 4.65 (2.20 – 9.84) ------------------------------------------------------------------------------------------ Persson et al. Diabetes Care 2009

Perinatal mortality in Type 1 diabetic pregnancies Gabbe and Graves 2003

Perinatal mortality in pregestational diabetic pregnancies Helsinki UCH 1951 - 2008

------------------------------------------------------------ Newborn Newborns/ Fetal Neonat. PM infants year deaths deaths %

--------------------------------------------------------------------1951-60 162 16 30 15 28.5 (3.2)*1959-68 231 23 25 23 20.8 (2.3)*1970-71 52 26 3 4 13.5 (1.7)*1975-80 279 47 3 3 2.2 (1.3)*1988-92 340 68 5 3 2.4 (0.8)*1993-97 362 72 5 4 2.5 (0.7)*1998-2002 330 66 4 1 1.5 (0.6)*2003-08 561 94 8 1 1.6 (0.5)* ------------------------------------------------------------------------------------------------*Annual mean in Finland

Incidence of Type 1 diabetes among children under 15 years of age in Finland 1953 – 2003 Tuomilehto et al. 2005

Vuosi

Perinatal deaths in pregestational diabetic pregnancies Helsinki UCH 1988 - 2008

-----------------------------------------------------------------------------------------No. White’s Gestation Birth weight Fetal/ Comment class (weeks + d) g z-score Neonat.-----------------------------------------------------------------------------------------1. B 23 + 5 575 .. F PROM2. C 25 + 1 370 -5.0 F Mult.MF3. C 25 + 1 500 -4.4 N RDS4. B T2 25 + 2 725 -2.8 N RDS5. B 26 + 0 440 -4.5 F Preeclampsia6. D 26 + 1 650 -2.8 F IVF, twin B7. C 26 + 3 830 -1.5 F Unexplained8. F 26 + 4 785 -2.1 N RDS9. R 27 + 2 1160 -0.4 F Pl.abruption10. C 27 + 4 400 -5.3 F Pl.abruption11. D 28 + 4 705 -3.8 N RDS12. D 29 + 2 1195 -1.3 F Plac. infarcts13. F 30 + 1 810 -3.9 N RDS14. F 30 + 1 1900 +1.7 N Severe MF -------------------------------------------------------------------------------------------------

Perinatal deaths in pregestational diabetic pregnancies Helsinki UCH, 1988 - 2008 (cont.)

-----------------------------------------------------------------------------------------No. White’s Gestation Birth weight Fetal/ Comment class (weeks + d) g z-score Neonat.-----------------------------------------------------------------------------------------15. B 31 + 1 1380 -1.6 F Cord compl.16. D 31 + 2 1255 -2.4 F Pl. abruption17. C 31 + 5 2160 +1.3 F Mat. ketoacid.18. B 33 + 6 1350 -3.4 F Plac. infarcts19. B 34 + 4 2310 -0.9 F Unexpl.Twin B20. D 35 + 4 4100 +3.4 N Sev. dystocia21. D 35 + 5 3150 +0.7 F Cord compl.22. C 36 + 0 4030 +2.9 F Unexplained23. B 36 + 1 2250 -1.8 F Pl. abruption24. R 36 + 3 4630 +4.5 F Unexplained25 B T2 36 + 4 5600 +6.4 F Unexplained26. C 36 + 6 2990 -0.5 F Unexplained27. B T2 37 + 3 6500 +7.8 F Unexplained28. C 37 + 5 3650 +0.7 F Fetal thrombosis29. D 38 + 1 3415 +0.2 F Unexplained30. C 38 + 4 4300 +1.8 F Shoulder dystocia31. D 39 + 2 5000 +3.0 N Heart MF

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Distribution of relative birth weight in IDDM pregnancies with (N=28) or without (N=1465) a perinatal death---------------------------------------------------------------BW z-score Perinatal death(SD-units) No Yes---------------------------------------------------------------< -2.0 3.2 % 43.5 %* -2.0 - +2.0 64.1 % 37.8 %> +2.0 32.7 % 21.7 %---------------------------------------------------------------*p < 0.0001

Last maternal HbA1c before delivery in IDDM pregnancies with (N=28) or without (N=1465) a perinatal death---------------------------------------------------------------

Perinatal deathNo Yes

---------------------------------------------------------------Median 6.8 % 7.6 % p=0.00595 % CI 5.3 - 9.0 5.4 - 12.0Number 1465 28---------------------------------------------------------------

Perinatal mortality in pregestational diabetic pregnancies ---------------------------------------------------------------1. Is increased especially among diabetics with poor glycemic control in the 3rd trimester

2. Over 40% occur before 30 weeks of pregnancy and many of these are growth restricted

3. ”Unexplained” fetal deaths after 35 weeks are most likely caused by chronic fetal hypoxia, and hence may be preventable---------------------------------------------------------------

Fetal och neonatal deaths between 32 och 40 pregnancy weeks in Type 1 diabetic pregnancies

Hagbard 1956

Stillbirth rate in diabetic and non-diabetic pregnancies according to birth weight in the United States 1995-97 Mondestin et al. AJOG 2002

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 g

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 g

100 %

10 %

1 %

0.1 %

Diabetic

Non-diabetic

Birth weight

Clinical evidence of chronic fetal hypoxia in Type 1 diabetic pregnancies---------------------------------------------------------------1. Increased frequency (12-25%) of abnormal fetal heart rate changes2. Increased frequency of acidosis at birth3. Fetal erytropoietin (EPO) levels are increased 4. Iron stores of fetal tissues are totally depleted in stillbirths5. Fetal deaths are 4-6 times more common than in the background population ---------------------------------------------------------------

Fetal factors causing fetal hypoxia in diabetic pregnancies--------------------------------------------------------------------------1. Fetal oxygen consumption increases during fetal hyperglycemia and hyperinsulinemia

2. The fetal oxyhemoglobin dissociation curve is shifted to the right, which tends to decrease placental oxygen transfer

3. Fetal polycythemia → increased blood viscosity and reduced capillary blood flow in fetal tissues

4. Hypertrophic cardiomyopathy → decreased cardiac output

5. Decreased intervillous blood flow (”placental insufficiency”), mainly in diabetic pregnancies complicated by preeclampsia and/or nephropathy

Fetal hyperinsulinemia at constant glucose concentration in chronically catheterized fetal sheep results -----------------------------------------------------------------------------------------

- in an 83% increase in fetal glucose utilization rate

- in a 73% increase in glucose oxidation rate

- in a 13% increase in oxygen consumption rate

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Hay et al. Quart J Exp Physiol 1986

Osmotic minipump for continuous insulin release placed in the thigh of a fetal Rhesus monkey

Susa et al: Diabetes 1979

Chronic hyperinsulinemia without maternal hyperglycemia results in fetal overgrowth in the Rhesus monkey Susa and Schwartz: Diabetes 1985

Umbilical arterial glucose (p<0.03), insulin (p<0.001) and erythropoietin (p<0.001) levels in control (open squares) and hyperinsulinemic (closed triangles) Rhesus fetuses Widness et al. JCI 1981

Arterial oxygen content decreases with increasing fetal insulin concentration in the fetal sheep

Milley et al. Am J Obstet Gynecol 1984

Amniotic fluid insulin levels correlate with cord plasma EPO levels at birth in Type 1 diabetic pregnancies

Widness et al. Diabetologia 1990

Negative correlation between fetal arterial O2 content and fetal plasma EPO-concentration in hyperglycemic fetal sheep Philipps et al. Proc Soc Exp Biol Med 1982

Negative correlation between UA pO2 at birth and AF EPO levels in Type 1 diabetic pregnancies (N=152) Teramo et al. Diabetologia 2004

Am EPO(mU/ml)

Umbilical artery pO2 (mmHg)

1

10

100

1000

10000

0 5 10 15 20 25 30 35

r= -0.62, p<0.0001

Experimental and clinical studies indicate that both maternal hyperglycemia and fetal hyperinsulinemia can independently cause fetal hypoxemia

Fetal hypoxemia

Maternal hyperglycemia

Fetal hyperglycemia

Fetal hyperinsulinemia

Experimental:

Carson eyt al. 1980 Widness et al. 1981 Philipps et al. 1982 Milley et al. 1984 Hay et al. 1986

Human studies:

Widness et al. 1981 Widness et al. 1990 Salvesen et al. 1993 Teramo et al. 2004

The fetus adapts to chronic hypoxia ---------------------------------------------------------------1. By redistributing its cardiac output in order to maintain adequate blood supply to the brain, heart and adrenals 2. By increasing EPO synthesis → increased erythropoiesis → increased oxygen carrying capacity (slow process)

3. By activating the transcription factor HIF- 1α → regulates tissue oxygenation locally (rapid process)---------------------------------------------------------------

Regulation of EPO and VEGF gene expression by HIF (hypoxia inducable factor):

Normoxia Hypoxia

Hydroxylation

HIF-1 alfa - OH

InactiveHIF-1 alfa

UbiquitylationProteolysis

PHD and FIH enzymes active

PHD and FIH enzymes inactive

Stable HIF-1 alfa

Active HIF-1alfa

EPO geneexpression ++

VEGF and

FETAL ERYTHROPOIETIN (EPO)---------------------------------------------------------------1. Regulates fetal erythropoiesis 2. Does not cross the placenta (molecular weight 34 kDa)3. EPO is not stored, hence plasma levels reflect rate of synthesis and elimination 4. EPO synthesis occures at least in the yolk sac, liver, kidneys, placenta and brain5. Has also protective properties in the brain (neurones, astrocytes) and in other tissues (retina, heart)---------------------------------------------------------------

Correlation between UV plasma and amniotic fluid EPO

levels in IDDM and HT pregnancies

1

10

100

1000

10000

1 10 100 1000 10000

Plasma EPO (mU/mL)

Am

nio

tic f

luid

EP

O (

mU

/mL

)

HT

IDDM

HT: r = 0.85, p<0.0001, N = 62

IDDM: r = 0.86, p<0.0001, N = 44

Correlation between simultaneously obtained AF and fetal plasma EPO levels at different AF EPO concentrations in HT and IDDM pregnancies

1

10

100

1000

10000

1 10 100 1000 10000

Plasma EPO (mU/mL)

Am

nio

tic flu

id E

PO

(m

U/m

L) Low: r= 0.45, p=0.0004

Intermediate: r= -0.09

High: r= 0.73, p=0.00003High

Low

Intermed.

Negative correlation between UA pH and AF EPO levels in pregnancies complicated by hypertension Teramo et al. JPM 2004

1

10

100

1000

10000

7.00 7.10 7.20 7.30 7.40

r = -0.61, p<0.0001, N=64AF EPO(mU/ml)

Umbilical artery pH

Amniotic fluid EPO levels increase exponentially in hypoxic fetuses (panel C) in HT pregnancies Teramo et al. JPM 2004

Exponentially increasing AF EPO levels in Type 1 diabetic pregnancies. The cross (+) is the AF EPO level one day after the fetus died. Teramo et al. Diabetologia 2004

A 26-year old White’s class C diabetic. AF EPO level increased exponentially. Emergency C/S because of late decelerations. Apgar scores 6/8, birth weight 4485 g (+3.7 SD-units).

Fetal and neonatal complications are more common in Type 1 diabetics with high AF EPO level (>60.0 mU/mL, N=21) than in diabetics with normal AF EPO level (<14.0 mU/mL, N=76) Teramo et al. 2004 ---------------------------------------------------------------Complication OR 95 % CI p---------------------------------------------------------------Macrosomia 5.4 1.9-15.3 0.0006(BW z-score>2.0 SD)

Hypoglycemia 11.3 3.8-33.7 <0.0001Cardiomyopathy 12.5 2.6-59.3 0.0001Hyperbilirubin. 5.9 1.9-18.4 0.0008NICU admission 3.4 1.1-10.8 0.037---------------------------------------------------------------

Positive correlation between mean maternal HbA1c during the last month before delivery and cord plasma EPO levels in Type 1 diabetic pregnancies(r = 0.57, p<0.0001, N = 44) Widness et al. Diabetologia 1990

Positive correlation between last maternal HbA1c and AF EPO levels in Type 1 diabetic pregnancies (N=155) Teramo et al. Diabetologia 2004

1

10

100

1000

10000

3 4 5 6 7 8 9 10 11 12

Hemoglobin A1c (%)

Am EPO (mU/ml)

r = 0.43, p<0.0001

In conclusion, in Type 1 diabetic pregnancies---------------------------------------------------------------1. Chronic intrauterine hypoxia (AF EPO >60.0 mU/ml) occurred in 14%

2. Increased AF EPO levels are associated with increased fetal and neonatal morbidity 3. It is possible to identify antenatally cases with high risk of intrauterine hypoxia and neonatal complications by measuring the AF EPO level---------------------------------------------------------------

Why does the fetus increase its EPO level in the plasma and in the

amniotic fluid?

Experimental studies show that during hypoxia both endogenous and exogenous EPO has neuroprotective properties in the brain ---------------------------------------------------------------Sakanaka M et al. In vivo evidence that erythropoietin protects neurons from ischemic damage. Proc Natl Acad Sci 1998;95:4635-40

Siren AL et al. Erythropoietin prevents neuronal apoptosis after cerebral ischemia and metabolic stress. Proc Natl Acad Sci 2001; 98: 4004-9

Chong ZZ et al. Hematopoietic factor erythropoietin fosters neuroprotection through novel signal transduction cascades. J Cerebr Blood Flow Metabol 2002; 22: 503-14

Siren AL et al. Global brain atrophy after unilateral parietal lesion and its prevention by erythropoietin. Brain 2006;129:480-9

--------------------------------------------------------------------------

swelling,

Clinical studies suggest that exogenous EPO has neuroprotective properties in the brain against hypoxia ---------------------------------------------------------------

Ehrenreich H et al. Erythropoietin therapy for acute stroke is both safe and beneficial. Mol Med 2002; 8: 495-505

Bierer R et al. Erythropoietin concentrations and neurodevelopmental outcome in preterm infants. Pediatrics 2006; 118: e635-4640

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Protection of neurones during hypoxia--------------------------------------------------------------------------

Hypoxia/ischemia Cytokines/growth factors

HIF-1α

EPO VEGF

Neurones Endothelial cells

Neuroprotection, Angiogenesis, proliferation,neurotrophic effect, decreasing apoptosisdecreasing apoptosis

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Marti H: J Exp Biol 2004

EPO concentration in fetal spinal fluid after iv. injection of EPO (5000 IU/kg) in fetal sheep

(Juul et al. Biol Neonate 2004)

Umbilical vein to artery concentration ratio of EPO as a function of pO2 in fetal sheep Davis et al. AJOG 2003

The placenta secrets 15 x more EPO than the kidneys during severe hypoxia in the fetal sheep --------------------------------------------------------------Mean secretion of EPO:

From the placenta 1.100 000 mU/h

From the kidneys 67 400 mU/h-------------------------------------------------------------

Davis et al. AJOG 2003

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

UV_UA_ratiox vs UA_pO2

UA_pO2

UV

_U

A_ra

tiox

UV

/UA

EP

O c

once

ntr

atio

n r

atio

Negative correlation between UV/UA EPO concentration ratio and UA pO2

Umbilical artery pO2 (kPa)

r = -0.48p = 0.033n = 20

Speculation:---------------------------------------------------------------1. The fetus regulates its erythropoiesis by small changes in EPO synthesis in the liver and the kidneys

2. In severe hypoxia the placenta starts to produce large amounts of EPO in order to protect the fetal brain (and other organs)---------------------------------------------------------------