Life Cycle Nutrition: Pregnancy

Follicular Phase

Days 1-14 menstrual cycle; day 1: blood flow begins; estrogen

Luteal Phase

Day 14-28; ovulation to menses; day 14: ovulation occurs; progesterone

Hormonal Regulation of Menstrual Cycle

end of menstrual cycle = ↓ estrogen → hypothalamus releases GnRH → signals anterior pituitary to release gonadotropins (FSH & LH)

Follicle Stimulating Hormone

stimulates the growth of ovarian follicles

Luteinizing Hormone

triggers ovulation and development of the corpus luteum

Corpus Luteum

produced when ovarian follicle ruptures

implantation occurs: releases progesterone to support pregnancy for first 3 months

no implantation: it dies and menstruation begins

Follicular/Proliferative Phase

follicle is maturing, low estrogen and progesterone; estrogen peaks at end of this phase

Luteal/Secretory Phase

endometrium thickens and prepares for implantation; progesterone ↑

Prostaglandins

contracts uterus during menstruation

Zygote

fertilized ovum; implantation occurs w/i 8-10 days

Morula

solid sphere of cells

Blastocyst

cells with a hollow cavity; contains trophoblast and inner cell mass

Trophoblast

becomes placenta

Inner Cell Mass

becomes fetus

Histotrophe

“uterine milk"; provides nutrients to the ovum

Implantation

occurs 8-10 days after fertilization, now called embryo and fetus (at 8 weeks)

Placenta

begins to grow at the same time as umbilical cord; stops growing at 8 weeks; acts as a “filter” of blood to fetus for nutrients; will be 1/6th of the weight of the fetus

Placental Functions

• Produce hormones & enzymes

• Exchange nutrients & gases w/ fetus

• Eliminate waste products from fetus

• Act as a barrier for some harmful products

Embryo Nutrition

most is provided by endometrium’s histotrophe until 8-12wks where the placenta takes over

Fetal Side of Placenta

villous chorion; trophoblast cells penetrate endometrium and villi develop—this creates a large surface area for nutrient and gas exchange

Maternal Side of Placenta

dicidua basalis; develops lacunae which are involved in nutrient exchange

Placenta Crossings

most large proteins cannot cross; glucose crosses through facilitated diffusion (is the primary fuel for fetus); lipids must be broken down before transfer, Hgb is independent in fetus

Placental Hormones

hCG, hCS, Progesterone, Estrogen, Lactation hormones

Zygote

first 2 weeks

Embryo

2-8 weeks

Fetus

8 weeks - term

Embryo Development

blastogenesis (by 2wks) → embryonic stage (by 60 days) → fetal stage (3rd mnth-term)

Cephalocaudal

top to bottom

Proximodistal

inside out

4 Stages of Cell Growth

hyperplasia (increase in cells) → hyperplasia-hypertrophy → hypertrophy → maturation

Fetal Weight Growth

1st Tri: slow gain

20wks: 10% birth weight attained

2nd half gestation: 90% weight gain occurs

Last 10wks: most fat is deposited

Protein deposition is constant throughout

Critical Period for NTD

17-30 days

Preconception Care

1. Risk assessment

2. Health promotion

3. Interventions to reduce risk

Nutrition Recommendations for Women Considering Pregnancy

• maintain a healthy weight

• follow MyPlate

• >400micrograms folic acid

• eat adq. iron sources

• <10,000IU vit. a from supplements daily

• avoid alcohol and herbs

Gravida

number of pregnancies

Para

delivery

Ab

abortion (spontaneous or therapeutic)

LC

live children

G5P4Ab1LC4

Gravida: 5, Para: 4, Ab: 1, LC: 4

Nulliparous

no previous pregnancies

Primiparous

one previous delivery

Multiparous

2+ previous deliveries

Weight Gain During Pregnancy

<18.5kg/m2 (Under): 28-40lbs

18.5-24.9kg/m2 (Normal): 25-35lbs

25-29.9kg/m2 (Over): 15-25lbs

30+kg/m2 (Obese): 11-20lbs

Twins: 25-54lbs

Maternal Anabolic Phase (Weeks 0-20)

• blood volume ↑, CO ↑

• fat, liver glycogen, nutrient stores ↑

• maternal organ growth

• ↑ appetite, food intake

• ↓ exercise tolerance

• ↑ anabolic hormones

Maternal Catabolic Phase (Weeks 20+)

• fat and nutrient store mobilization

• ↑ prod. blood glucose, lipids, ↓ liver glycogen stores

• ↑ fasting metabolism

• ↑ appetite, intake decline ↓ near term

• ↑ catabolic hormone levels

Blood Volume Changes

• ↑ blood volume (20%; hypervolemia)

• ↑ plasma volume (50%)

• hemodilution “dilution effect” with blood volume ↑

• multigravida = ↑ fluid even more

• plasma volume is correlated with pregnancy outcome

Pregnancy Blood Composition

• ↑ RBC volume (18-30%)

• Hgb + HCT ↓ (due to fluid ↑)

Cardiovascular System During Pregnancy

• heart slightly enlarges

• ↑ CO (~30-50%)

• 1st Tri: BP ↓

• ↑ HR 16%

Respiration During Pregnancy

• ↑ maternal O2 consumption (~10%)

• diaphragm elevates

• respiratory system ↑ efficiency

• ↑ tidal volume (30-40%)

Metabolic Changes During Pregnancy

• ↑ body temp.

• ↑ BMR 15% by 2nd half of pregnancy (returns to normal 5-6 days postpartum)

Renal Function Changes During Pregnancy

• 7-10L water added to total body weight

• dilation in the whole renal system

• ↑ GFR (glomerular filtration rate)

• ↓ ability to excrete water

• more susceptible to UTIs

GI Function

• relaxed GI muscle tone

• ↑ appetite and thirst

• changes in taste

• ↓ motility in tract

• ↓ intestinal secretions

• nutrient absorption ↑

Immune Changes During Pregnancy

• system becomes suppressed to allow the body to not recognize the fetus as “foreign”

• causes the body to be more susceptible to infections

• pro-oxidative, high stress state

CHO Metabolism During Pregnancy

glucose is the key placental nutrient; maternal blood glucose ↑; insulin resistance is normal in pregnancy

Protein Metabolism During Pregnancy

new tissue synthesis is occuring; ~2lbs protein is accumulated total; protein consumption must ↑ in diet

Fat Metabolism During Pregnancy

1st ½ Pregnancy: maternal fat storage

2nd ½ Pregnancy: fat mobilization

blood lipid values ↑, but it’s not related to dietary intake

Energy Utilization Changes During Pregnancy

Fat: main maternal fuel

Glucose: main fetal fuel

Progesterone Function

• Primary function: relax smooth muscles of uterus and GI tract

• Induced maternal fat deposition

• ↑ sodium excretion by kidneys

• ↑ breast development

Estrogen Function

• Promotes uterus and endometrial growth

• ↑ breast development

• Controls uterus function

• ↑ hygroscopic (water absorption) properties of connective tissue (↑ flexibility!)

Dizygotic Twins

“fraternal”; two eggs fertilized; 50% same sex, 50% different sexes

Monozygotic Twins

“identical”; one egg fertilized, then splits; always the same sex

Twin Womb Sharing

placentas, aminotic sacs, and chorion can be shared between twins

Risks for Multifetal Pregnancies

• preeclampsia

• iron-def. anemia

• gestational diabetes

• placenta previa (placenta covers the cervix)

• neonatal death

• pre-term birth

• low birth weight, etc.

Maternal Weight Gain with Twins

1st Tri: 5-7lbs

2nd & 3rd Tri: 1-2lbs/week

~41lbs total for a normal weight woman; +450kcals/day

Energy Needs During Pregnancy

• 1st Trimester: same as pre-pregnancy needs

• 2nd Trimester: +340kcals/day

• 3rd Trimester: +452kcals/day

• Total: ~300kcals/day

Carbohydrate Intake Recommendations

• ~45-65% total kcals (same as normal DRI)

• >175g/day

• 25-35g fiber daily

• ↑ glycemic index foods can affect the fetus

Protein Intake Recommendations

• 1st Trimester: 0.8g/kg/day

• 2nd Trimester: 1.1g/kg/day

• ~70-80g/day total

• (~925g deposited into the fetus)

First Trimester

Weeks 0-12

Second Trimester

Weeks 13-27

Third Trimester

Weeks 28-Term

Nutrients of Concern for Vegetarian/Vegan Diet

• low calorie consumption

• vit. D & B12

• calcium

• zinc

• omega-3’s

• iron

Fat Intake Recommendations

• linoleic (omega 6) & alpha-linoleic (omega 3)

  • important in fetal brain, retinal, and neural tissue development

• DHA & EPA (synth. from alpha-linoleic):

  • found in fish, seafood, fish oils

  • DHA in egg yolks and orange juice

Calcium Intake Recommendations

absorption ↑ and excretion ↓

• 1000mg/day (>19yrs)

• 1300mg/day (<19yrs)

rule of 300’s!

Rule of 300s

• 1c milk = 300mg calcium

• 1c yogurt = 300mg calcium

• 1.5oz cheese = 300mg calcium

• balanced diet = 300mg calcium

Iron Intake Recommendations

• needs are greatly ↑ during pregnancy

• absorption ↑ 10-30%

• fetus accumulates most in the last trimester

• 27mg/day

• supplement absorption is poor

Ferrous Sulfate Iron Content

20%

Ferrous Gluconate Iron Content

12%

Ferrous Fumarate Iron Content

32%

Iron Deficiency Anemia During Pregnancy

rates are high; risks include pre-term delivery, low birth weight, low iron stores in newborn

Vitamin A Needs

<5000IU/day

Vitamin D Needs

some women at risk for deficiency; 2-15min in sun/day & 3c milk; supplements for deficiency

Folate Needs

NTD at risk when deficient; preconception intake is extremely important

Types of Neural Tube Defects

• spina bifida (~60% birth cases)

• anencephaly (~30%)

• encephalocele (~10%)

Alpha-Feto Protein Test (AFP)

blood test given in 16-18wks pregnancy; may suggest NTD if positive (there are many false + and -); AFP is made in fetal liver

Folate Bioavailability

• supplements: ~100%

• fortified foods: ~85%

• food: ~50%

Folate DRI

400ug/day (pre-pregnancy)

600ug/day (pregnancy)

• 400ug from fortified foods/supplements

• 200ug from fruits/vegetables

Prenatal Vitamins

• with exception of iron and folic acid, nutrient needs can be met with well balanced diet

• women at higher risk:

  • poor diets, vegan, smokers, alcohol/drug use

  • multifetal pregnancy

  • IDA/other nutrient deficiencies

Things to Avoid Whilst Pregnant

• unpasteurized soft cheeses

• cold cuts

• cat litter

• herbal teas

• hot tubs/saunas

• caffeine (will cross placenta, just be mindful!)

Obesity and Pregnancy

• ↑ risk of gestational DM & hypertension

• ↑ blood glucose; ↑ C-reactive protein; ↑ insulin + BP; dyslipidemia + insulin resistance

Risks with Maternal Obesity

• preeclampsia; gestational DM

• blood clots

• UTIs

• ↑ perinatal mortality in fetus; ↑ rates LGA + C-section

• advice: preconception weight loss!

• bariatric surgery = wait 1-2yrs

Underweight Mothers

• ↑ risk preterm + SGA infants

• premature membrane rupture

• weight gain must be 28-40lbs

Gynecologic Age

age of 1st pregnancy - age of menarche = (<3yrs is greatest risk)

Older Women in Pregnancy

• >35yrs = ↑ risk

• placenta previa

• abruption placenta

• macrosomia: LGA fetus

Pregorexia

term used to characterize mothers with anorexic disorder

N/V Treatment

• ↑ CHO foods (low fat)

• eat before getting out of bed

• have small, frequent meals

• Vitamin B6 (pyridoxine)

• Diclectin (B6 + sleeping meds)

• Ginger! (1g/day for 4 days)

Hyperemesis Gravidarum

severe N/V through most of pregnancy; 1-2% pregnancies; ↑ weight loss, electrolyte imbalances and dehydration

Heartburn Treatment

• small frequent meals

• avoid foods that will aggravate

• avoid tight clothes

• ↑ fiber

• sleep elevated

Constipation/Flatulance

• ↑ fiber intake

• ↑ fluid intake

• avoid laxatives (they dehydrate)

• soluble fiber (safe)

Chronic Hypertension (HTN)

• present before pregnancy or <20wks

• 3% incidence

• ↑ rates in non-hisp. black am., obese, ↑ 35yrs, etc.

Gestational Hypertension

only hypertensive when pregnant