During pregnancy and lactation, calcium requirements increase substantially to support the developing fetus and breastfeeding infant. The placenta transfers 200-300mg of calcium daily to the fetus during pregnancy, while breastmilk contains 280-400mg of calcium that is secreted daily during lactation. To meet these demands, women undergo physiological adaptations like increased intestinal calcium absorption facilitated by elevated vitamin D and intestinal calbindin levels. They also experience decreased urinary calcium excretion through effects of PTHrP and estrogen. These changes, along with calcium mobilization from maternal bones, enable women to direct calcium to the fetus and breastmilk. Low calcium intake can potentially impact fetal and infant growth and development as well as maternal bone health.

2. INTRODUCTIONINTRODUCTION
• During gestation the average foetus
requires about 30 g of calcium to mineralize
its skeleton and maintain normal
physiological processes.
• The suckling neonate requires more than
this amount in breast milk during six
months of exclusive lactation
• Although pregnant and lactating women
face a comparable demand in the amount of
calcium

3. • During pregnancy and lactation, 200–300
mg Ca/d is eithertransferred via the
placenta to the foetus or excreted in breast
milk.
• The provision of calcium during pregnancy
and lactationrequires
– Physiologic adaptation of calcium homeostatic
mechanisms.
– Including
1. intestinal calcium absorption
2. urinary calcium excretion
3. maternal bone calcium turnover

5. TABLE
Selected examples of recommended dietary
allowances for calcium in different countries
Women Pregnancy Lactation
mg/d mg/d mg/d
Australia-1989 800 1100(+300) 1200(+400)
FAO/WHO
1974+
450 1100(+650) 1100(+650)
France 1988 800 1000(+200) 1200(+400)
Indonesia 1980 500 600(+100) 600(+100)
Ireland 1984 800 1200(+400) 1200(+400)
Spain 1983+ 600 1325(+725) 1425(+825)
United Kingdom
1991
700 700(0) 1250(+550)
United States
1989
800 1200(+400) 1200(+400)

6. • Calcium stress of pregnancy is
relatively similar among women
• The amount of calcium secreted
during lactation can be highly
variable, depending on
1. Amount of breast-milk produced
2. Breast-milk calcium concentration
3. Length of the lactation period

7. Calcium
• Calcium is important for a number of
functions in the body
• It is essential for
1. Growth
2. Maintenance of bones and teeth
3. Nerve transmission
4. Muscle contraction
5. Number of other cell processes

8. • The body has increased calcium needs
during growth spurts, pregnancy and
lactation
• An inadequate calcium intake can therefore
cause a number of problems
• In growing children and adolescents, this
can lead to stunted growth, and a reduced
peak bone density increasing the risk of
osteoporosis later in life
• In pregnancy, the unborn child will draw on
the mother’s calcium stores to meet its
needs, putting the condition of the mother’s
bones and teeth at risk

9. Recommended Daily Intake
Population Group RDI
Adults 800 mg/day
Pregnancy 1100 mg/day
Lactation 1300 mg/day
Elderly 1000 mg/day

10. Sources of calcium
Food Serving size Calcium (mg)
Full cream Milk 250 ml (1 glass) 285
Natural Yoghurt 200g (1 tub) 340
Cheddar cheese 2 slices (40g) 310
Cooked Spinach 1 cup (100g) 170
Cooked broccoli 1 cup (100g) 30
Canned salmon (plus
bones)
100g 230
Canned salmon (plus
bones)
3 sardines (50g) 190
Almonds 45g 50

11. Availability in the diet
• Reduce calcium’s availability and
absorption in the gut:
1. Fibre – soluble pectin fibre binds with the
calcium
2. Fat – forms a soap in the stomach when it
binds with calcium
3. Phytic acid – found in breakfast cereals
4. Oxalic acid – found in high concentrations in
spinach and rhubarb, and in smaller amounts
in sweet potatoes and dried beans.

12. Including calcium in the diet
• It’s easy to include dairy foods in a healthy,
balanced diet. Have a look at these simple
ideas:
– Have some milk with your breakfast cereal
– Wake up to a home-made banana, mango or
strawberry smoothie
– Try some cheese on toast
– Nothing beats cream cheese on a bagel

13. –Try yoghurt at morning tea to keep you
going until lunch
–Sprinkle some cheese on your potato
–Have some fresh fruit and yoghurt for
dessert
–Enjoy a warm cup of milk before bed

14. If dairy foods are not consumed there
are many other ways to incorporate
calcium into your diet:
–Try some calcium-enriched soymilk with
muesli
–Have tuna and tomato on toast for
breakfast
– Use calcium-fortified bread to make a
sandwich
–Snack on a handful of nuts
–Have a stirfry of Asian green vegies

15. Pregnancy
• The normal foetal skeleton has accreted
about 30 g calcium by theend of gestation
• About 80% of the accretion occurs rapidly
duringthe third trimester
• Daily accretion rate ofabout 250–300 mg
calcium by the foetal skeleton duringthe
third trimester

16. The mother could theoretically
meet this demand by
Increasing the intestinal absorption
Decreasingrenal calcium losses
Increasing the resorption of calciumfrom
the maternal skeleton

17. Minerals and hormones
• Earliest apparent changes in calcium
balance in pregnancyis a fall in total serum
calcium
• Serum calcitoninlevels are increased during
pregnancy
• PTHrP levels have been increased during
pregnancy
• Other hormones are clearly in flux during
pregnancy

18. Intestinal calcium absorption
• Intestinal absorption of calcium is doubled
during pregnancy
• The increase inintestinal calcium
absorption is associated with
– Doublingof 1,25-dihydroxyvitamin D levels
– Increased intestinal expressionof the vitamin D-
dependent calcium-binding protein calbindin-D

19. Renal calcium excretion
• The 24-h urine calcium excretion is
typically increased as early asthe 12th week
of gestation
• This increaseis likely a consequence of
– Increased intestinal absorptionof calcium
– Increased renal filtered load of calcium
– Increased glomerular filtration rate
• In the fasted state, the calcium excretionis
normal or even low.

20. Osteoporosis in pregnancy
• Occasionally, a woman will suffer an
apparent fragility fracture during
pregnancy or in the first few weeks after
delivery
• low bonemineral density reading will be
obtained
• Focal, transient osteoporosis of the hip is a
rare

21. Lactation
• The typical daily loss of calcium in breast
milk has been estimatedto range from 280–
400 mg
• Although daily losses as greatas 1000 mg
• A temporary demineralizationof the
skeleton seems to be the main mechanism

22. Again, the mother could
theoretically meet this demand by
• increasing the intestinal absorption of
calcium
• decreasing renal calcium losses
• increasing the resorptionof calcium from
the maternal skeleton

23. Minerals and hormones
• The mean ionized calcium level of
exclusively lactating womenis increased,
although it remains in the normal range
• Serumphosphate levels are also increased
and may exceed the normalrange
• Intact PTH,as determined by a two-site
IRMA, has been found to be reduced50%
or more in lactating women in the first
several months postpartum

24. Intestinal calcium absorption
• The intestinal absorption of calcium is
equal to the no pregnant state
–Decreased from pregnancy
• This change coincides with thefall in 1,25-
dihydroxyvitamin D levels to normal.

25. Renal calcium excretion
• The GFR falls during lactation to a level
below the pregnantand pre pregnant value
• Tubular reabsorption of calcium must be
increased
• Renal excretion of calcium is typically
reduced to levels as low as 50 mg/24 h
• increased serum calcium

26. • Acute estrogen deficiency (e.g. GnRH
analog therapy)
→increases skeletal resorption and
→raises the blood calcium;
→in turn, PTH is suppressed and
→renal calcium losses are increased.

27. • During lactation, the combined effects of
PTHrP (secreted by the breast) and
estrogen deficiency
→increase skeletal resorption
→reduce renal calcium losses, and
→raise the blood calcium,
→but calcium is directed into breast milk.

28.
Acute estrogen deficiency (e.g. GnRH analog therapy) increases skeletal resorption and
raises the blood calcium; in turn, PTH is suppressed and renal calcium losses are increased.
During lactation, the combined effects of PTHrP (secreted by the breast) and estrogen
deficiency increase skeletal resorption, reduce renal calcium losses, and raise the blood
calcium, but calcium is directed into breast milk.

29. Osteoporosis of lactation
• Like osteoporosis inpregnancy
• Woman may have had low bone density
before conception
• PTHrP levels were high in one case of
lactational osteoporosis

30. CALCIUM PHYSIOLOGY
DURING PREGNANCY
• Calcium provided from the maternal
deciduas aids in fertilization of the egg and
implantation of the blastocyst
• About 80% of the calcium present in the
foetal skeleton at the end of gestation
crossed the placenta during the third
trimester
• Intestinal calcium absorption doubles
during pregnancy

31. Bone mobilization
• Investigated changes in bone mineral
content during pregnancy and lactation
• Bone loss at certain skeletal sites, such as
the lumbar spine and femoral neck

32. Mineral Ions
• Several characteristic changes in maternal
serum chemistries and calciotropic
hormones during pregnancy
• Serum albumin and hemoglobin fall during
pregnancy due to hemodilution
• Serum phosphate and magnesium levels
remain normal during pregnancy.

33. Schematic illustration of the longitudinal
changes in calcium during pregnancy and
lactation.

34. Schematic illustration of the longitudinal
changes in phosphate PTH during pregnancy
and lactation.

35. Schematic illustration of the longitudinal changes in
25-hydroxyvitamin D or calcifediol (25-D), Calcitonin
during pregnancy and lactation.

36. Schematic illustration of the longitudinal
changes in calcium during pregnancy and
lactation.

37. Parathyroid Hormone
• Parathyroid hormone (PTH) was first
measured with assays that reported high
circulating levels during pregnancy
• Those early-generation PTH assays
measured many biologically inactive
fragments of PTH
• In contrast, in women from Asia and Gambia
who have very low dietary calcium intakes

38. Vitamin D Metabolites
• A common concern is that the placenta and
fetus will deplete maternal 25-D stores, but
this does not appear to be the case
• Even in severely vitamin D deficient women
there was either no change or at most a
nonsignificant decline in maternal 25-D
levels during pregnancy.

39. Calcitonin
• Serum calcitonin levels are increased
during pregnancy and may derive from
– Maternal Thyroid
– Breast
– Decidua
– Placenta
• Calcitonin plays an important role in the
physiological responses to the calcium
demands of pregnancy

40. PTHrP
• PTHrP levels are increased during the third
trimester
– but whether this occurs earlier in pregnancy
• PTHrP is produced by many tissues in the
fetus and mother and it is unknown which
source(s) account for the rise in PTHrP 1-86
detected in the maternal circulation

41. Other Hormones
• Calciotropic hormones
–Response to challenges such as
hypocalcemia
• Steroids
• Prolactin
• Placental lactogen
• IGF-1

42. Renal Handling of Calcium
• Renal calcium excretion is increased as
early as the 12th week of gestation and 24
hour urine values (corrected for creatinine
excretion) can exceed the normal range.
• Conversely, fasting urine calcium values are
normal or low, confirming that the
hypercalciuria is a consequence of the
enhanced intestinal calcium absorption.

43. Consequences of bone loss during
pregnancy and Lactation
• Maternal bone loss during pregnancy or
lactation might lead to osteoporosis and
fracture either contemporaneously or, by
reducing peak bone mass, in later life.
• Severe bone loss leading to osteoporosis and
fracture is a well recognized but rare
complication of pregnancy and lactation

44. Influence of calcium intakes on
breast-milk calcium secretion
• Breast-milk calcium secretion is known to
be independent of recent maternal calcium
intake
• No relationships between breast-milk
calcium concentrations and maternal
calcium intakes
• However, there have been no definitive
investigations in women with low calcium
intakes.

45. Effect of maternal calcium intake
on foetal and infant growth
• Marginal calcium deficiency may be
associated with reduced bone mineral
content
• The influence of maternal calcium intakes
during pregnancy and lactation on the
growth and bone development of the foetus
and breast-fed baby is not known

46. Calcium intakes and hypertensive
disorders of pregnancy
• A potential connection between low calcium
intakes and hypertensive disorders in
pregnancy was suggested by the fact that
the incidence of eclampsia is highest in
countries where calcium intakes are low.
• Several well-conducted trials have studied
the efficacy of calcium supplements in
preventing preeclampsia, gestational
hypertension, and premature delivery, as
summarized in Table

48. Biochemical changes during
pregnancy and lactation
• Calcium absorption is increased in
pregnant women.
• The role of parathyroid hormone is unclear,
since recent use of a more specific
radioimmunoassay has cast doubt on
previous reports of increased parathyroid
hormone concentrations in pregnancy

49. During lactation………….
• Urinary calcium excretion is generally
decreased.
• Increased calcium absorption may occur.
• No differences in fractional absorption have
been found during established lactation
between breast-feeding mothers and control
subjects

50. Adverse effects of increases in
calcium intakes
• Very high calcium intakes are believed to
increase the risk of kidney stones
• Renal calculi occur in 1/1500 pregnancies
• The potential for urinary tract infection
may be increased when urinary calcium
excretion rises as a result of calcium
supplementation

51. • In addition, increases in dietary
calcium consumption have been
associated with reduced absorption
of other minerals
• such as
–Iron
–Zinc
–Magnesium

52. DISORDERS OF
CALCIUM AND BONE
METABOLISM
DURING PREGNANCY
&
LACTATION

53. Osteoporosis in Pregnancy
• In such cases it is not possible to exclude the
possibility that low bone density or skeletal
fragility preceded pregnancy
• Osteoporosis in pregnancy usually presents
in a first pregnancy at age 27-28 and there
is no increased risk with higher parity
• Fractures tend not to recur in subsequent
pregnancies

54. Other disorders
• Low Calcium Intake
• Hypoparathyroidism
• Primary Hyperparathyroidism

56. Why you need calcium during
pregnancy
• Baby needs calcium to build strong
bones and teeth
• Grow a healthy heart, nerves, and
muscles
• Develop a normal heart rhythm and
blood-clotting abilities
• Reduce bone resorption