Pregnancy Physiology & Conditions

Dr Hadi Esmaily PharmD.

Pregnancy CheckβhCG & αhCGTypesAccuracyFalse negative:

1. Done before the first day of a missed period

2. Urine is not at room temperature3. Ectopic pregnancy4. History of ovarian cysts (PCOs)5. Menotropins or chorionic gonadotropin

TerminologyParity: Number of deliveries after 20

weeks' gestationGravida: Number of pregnanciesExample: a Pregnant woman who

has previously delivered one set of twins & had 1 abortions is described as a gravida 3, para 1 (G3, P1)

Perinatal period: 20th week of gestation -28th day after birth

Terminology Cont.Gestational age: the time from the

start of the last menstrual cycleAbortion: a delivery before 20 weeks'

gestationPreterm birth A fetus delivered

between 20-37 weeks' gestationTerm infant: A fetus delivered

between 37-42 weeks' gestationPostmaturity birth: A fetus delivered

after 42 weeks' gestation

Pregnancy PhysiologyConception begins after

fertilization of an ovumAfter 5-6 days, blastocyst

adheres to the endometriumIt secretes hCG, maintains the

corpus luteum so that menstruation is prevented & pregnancy can continue

Pregnancy Physiology8-10 days after conception, hCG

can be measuredPlacenta serves as a strong

barrier but a few cells are able to cross

Date of Confinementseveral methods:

1. LMp2. Pelvic Examination3. Uterine Size4. Fetal parameters by ultrasound

Add 7 days to the first day of the LMp, subtract 3 m & add 1 y (Naegele rule)

Vitamins & Minerals Supplementation

Nutritional status should be assessed preconceptionally with the goal of optimizing maternal, fetal, & infant health

Iron Iron requirements ↑ because:

1. Maternal blood volume expansion

2. Fetal needs3. Placenta cord needs4. Blood loss at the time of

delivery5. Some women may already have

inadequate body stores of iron before pregnancy

Iron supplementation is necessaryA pregnant woman needs

about 18 to 21 mg iron/day(15-50% ↑Absorption)

Anemia in PregnancyAnemia in Pregnancy:

◦1st & 3rd Trimester: Hb<11◦Second Trimester: Hb<10.5

The classic morphologic changes outside of pregnancy, are not prominent in pregnant women.

Women with iron deficiency needs 60-120 mg iron daily

Folic AcidThe RDA of Folic Acid in

pregnancy is 0.6 mg (0.4-0.8)women who receive folic acid

daily during the first trimester are less likely to have a child with neural tube defects (Spina Bifida & Anencephaly)

CalciumCa is needed for adequate

mineralization of skeleton & teeth, esp. in the 3rd trim. as teeth formed

The RDA in pregnancy◦1,000 mg/day for women >19 y ◦1,300 mg/day for women <19 y

Pregnancy-Induced Pharmacokinetic ChangesPhysiologic changes can alter the

absorption, distribution, metabolism, & elimination of drugs.

Factors influence pharmacokinetics of drugs:1. Maternal physiologic changes 2. The effects of the placental-fetal

compartment

Nausea & Vomiting50-80% during 5-12 weeks of

gestation~ 91% of cases will resolve by 20

wManagement:

1. Non Pharmacologic2. Pharmacologic

Non Pharmacologic ManagementSmaller frequent meals consisting

of a low-fat, bland, & dry diet (e.g., bananas, crackers, rice, toast)

Avoid spicy & highly aromatic foodsTake prenatal vitamins with iron at

night High protein mealsRest Avoidance of the sensory stimuli

Pharmacologic ManagementModerate-Severe N/V that

nonpharmacologic fails or threatens metabolic or nutritional status

H1 receptor blockers & Pyridoxine (B6)(Diphenhydramine, Hydroxyzine,

Dimenhydrinate)Phenothiazines or Metoclopramide if

antihistamines fail

Dosing of Pharmacologic Management

Medications Used for Nausea & Vomiting during Pregnancy

Drug Dose Pregnancy CategoryPyridoxine 10–25 mg PO three to four times

dailyA

Diphenydramine 25–50 mg PO, IV, IM every 4–6 hrs B

Hydroxyzine 25–50 mg PO every 6–8 hrs CPromethazine 12.5–25 mg PO, PRN every 6 hrs C

Metoclopramide 5–10 mg PO, IM, IV every 8 hrs B

Ondansetron 4–8 mg PO, IV every 8 hrs B

Ginger (Zingiber Officinale)Randomized trials and

controlled studies suggest that powdered ginger is more effective than placebo, and equivalent to vitamin B6

↑ Adverse effects on pregnancy outcome has not been reported, but larger studies are needed

Reflux EsophagitisReflux esophagitis/heartburn is affecting

2/3 of womenEnlarging uterus ↑Intra-abdominal

pressure, & estrogen/progesterone relax the esophageal sphincter

Management:1. Lifestyle Modification2. Calcium Carbonate3. Aluminum Antacids4. H2 Blockers5. PPIs

Urinary Tract InfectionsIt is one of the most common

complications of pregnancy Changes leads to bacteriuria

1. Enlarged uterus (compress the ureters)

2. ↑Progesterone → Relaxation of ureteral muscle

3. Urine alkalization4. Glucosuria

Asymptomatic Bacteriuria Versus

Acute Cystitis>105 CFU of bacteria, obtained by 2

consecutive clean-catch samples If in the absence of any urinary

symptomsAsymptomatic Bacteriuria

If with frequency, urgency, dysuria, and hematuria without fever

Acute Cystitis

Urinary Tract Infections Cont.If ASBs are left untreated lead to

pyelonephritis, low-birth-weight infants, and premature delivery

Most common pathogens:1. E. coli2. Klebsiella pneumonia3. Proteus mirabilis,4. Enterobarter species

Urinary Tract Infections Cont.

Common Antibacterials:1. Penicillins2. Cephalosporins3. Nitrofurantoin

Pyelonephritis in Pregnancy1-2%Leads to sepsisParental Antibiotics:

◦Cefazolin 2 g IV every 8 hours◦Gentamycin (targeted peak of 8 mcg/mL and

trough less than 1 mcg/mL)Continued for at least 48 hours after

becoming afebrileThen Continue orally cephalexin 500 mg

PO four times daily for a total of 10-14 days of antibiotic therapy (PO+IV)

Diabetes MellitusPregestational DiabetesGestational Diabetes Mellitus (GDM)Goal:

1. FPG: <90 mg/dL2. Premeal <100 mg/dL3. l-hour postprandial: 100-120 mg/dL4. Hb-Alc levels in the normal range (4.5-

5) Insulin Versus Oral Hypoglycemics

HTNHypertension in pregnancy:

1. Systolic BP>140 mm Hg 2. Diastolic BP>90 mm Hg

Management:1. Methyldopa2. Labetalol3. Nifedipine

Prevention of RhD Alloimmunization

Blood group incompatibility between a pregnant woman and her fetus

Leads to alloimmunization of the mother and hemolytic anemia in the fetus

An Rh D-negative mother becomes immunized after exposure to fetal erythrocytes that carry the D antigen

As little as 0.1 mL of blood can immunize a human

The severity of HDN depends on the concentration of maternal antibodies

Prevention of RhD Alloimmunization

RhoGAM® (300 mcg IM)Antepartum Prophylaxis

◦Giving RhD Ig IM at 28 weeks' gestation

Postpartum Prophylaxis◦A second dose of RhD Ig should be

repeated within 72h of delivery

Drugs In Pregnancy and lactation Briggs

PregnancyCase ReportsLactationClinical

Management

Drugs in Pregnancy

A: SafeB: Human Studies Show No RiskC: The Risk Can Not Be Ruled OutD: Positive Evidence Of RiskX: Contraindicated

Drugs Suspected/Proven to be Human TeratogenAlcoholACEIs, ARBAminopterinAndrogensBexaroteneBosentanCarbamazepineChloramphenicolCocaineCorticosteroids

CyclophosphamideDanazolDiethylstilbestrol

(DES)EfavirenzEtretinateIsotretinoinLeflunomideLithium

MethimazoleMethotrexateMisoprostolMycophenolateParoxetinePenicillaminePhenobarbitalPhenytoinRadioactive iodineRibavirin

StatinsStreptomycinTamoxifenTetracyclineThalidomideTretinoinValproateWarfarin

Drugs Suspected/Proven to be Human Teratogen

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