Persistent uterine contractions (4 in 20 or 8 in 60) and change in dilation and/or effacement (>80%) of the cervix prior to 37 weeks gestational age.  (Gabbe)

History of PTL

Preterm ruptured membranes

Preeclampsia

Abruptio placenta

Multiple gestation

Placenta previa

Fetal growth retardation

Excessive or inadequate amniotic fluid

Fetal anomalies

Amnionitis

Incompetent cervix

Diabetes

Asthma

Drug Abuse

Pyelonephritis

Anemia (Hgb <10)

Bacteriuria

BV

Cervical injury or abnormality

Uterine anomaly or fibroids

Excessive uterine contractility 

Premature cervical dilation of more than 1cm or effacement of >80%

Periodontal disease (though this is questionable)

• Maternal race (black more than non-black)
• Low socioeconomic status
• Poor nutrition
• Low pre-pregnancy weight
• History of previous preterm birth
• Absent or inadequate prenatal care
• Age less than 18 or more than 40
• Strenuous work
• High personal stress
• Cigarette smoking

Starting at between 16 and 24 weeks, she should be offered progesterone regardless of transvaginal ultrasound cervical length

(ACOG)

Women at risk for preterm labor:

1) screen and treat all women for asymptomatic bacteremia in pregnancy

2) If BMI<19, counsel women on recommended weight gain

3) encourage women to eat Mediterranean-type diet, low in fat and processed food, rich in fruits and vegetables and two servings fatty fish or omega 3 supplements

5) Vitamin D supplementation if necessary

6) Screen and treat for BV

7) Support pregnant women in smoking cessation

8) Refer women for drug treatment if using cocaine

9) Consult regarding prophylactic progesterone therapy with previous PTB with singleton

10) obtain 2nd trimester US for cervical length, consult if < 25 mm

11) perform cervical exams starting at 28 weeks or at same time PTL started in previous pregnancy or with symptoms

Risk after 1 PTB: 15%

Risk after 2 PTB: 33-70% (depending on source)

Term pregnancy followed by PTB: 24%

U/cs

Back pain -- constant or intermittent

Menstrual type cramping

Pelvic pressure

Change in vaginal discharge

Vaginal spotting or bleeding

1. Note if febrile
2. Palpate abdomen and uterus for tenderness and presence of u/c’s
3. Perform gentle spec exam to obtain fFN specimen (this must be done before any examination of the cervix and other vaginal and cervical cultures)
4. Check cervix for position; consistency; dilation; effacement (length); and station of presenting part
5. Assess urine for nitrites and leukocytes; and culture and sensitivity if with signs and symptoms of preterm labor.

-screen for asx bacteriuria, treat if positive

-if BMI <19, counsel re: weight gain, nutritionist referral

-encourage Mediterranean diet, fruits, veggies, fish

-ensure adequacy of Vit D, supplement PRN

-?screen for BV (in women with hx PTB)

-referral for smoking cessation, drug tx

-in women with prior PTB, consult re: progesterone prophylaxis

-check cervical length on second tri u/s; consult if <25mm

-perform cervical exams starting at 28 weeks (or whenever prior PTL began), or with sx

-obtain clean catch urine to r/o UTI

-abdominal exam to assess contractions and tenderness, use toco if available

[depending on setting, may need to refer to birthing unit for further eval ie the below assessments]

-obtain fFN

-obtain GBS sample and other vag infxns PRN

-perform digital cervical exam

-observe and recheck cervix after 2 hours.

*if she meets diagnostic criteria for PTL, refer to birthing unit for further eval

-gestational age 20-36 weeks

-documented regular contractions

-one of the following: ROM, documented cervical change, dilation 2+ cm, effacement 80%+

Obstetrical hx- specifically previous hx of PTL and hx of pregnancy losses, hx of uterine/cervical infection during pregnancy, mechanical trauma during birth.

Gyn hx- any surgeries to the cervix, cervical cancer. Any congenital or acquired cervical abnormalities.

Inquire about symptoms such as pelvic pressure, cramping or backache, and increased vaginal discharge.

Transvaginal ultrasound

Physical exam may show effaced or dilated cervix

Cerclage

Vaginal progesterone

Placement of pessary

When would you use antenatal corticosteroids?

What is the rationale for giving corticosteroids?

A single course of corticosteroids is recommended for women between 24 & 34 weeks pregnant who are at risk for preterm delivery within 7 days.

The steroids will help with lung maturation and help give other organ systems a leg up.  Result - fewer pre term babies experience severe respiratory distress, intracranial hemorrhage, necrotizing enterocolitis, and death if their mothers received antenatal corticosteroids in the recommended time period.  

 There is not a lot of great data supporting administration of corticosteroids after 34 weeks and it appears to suppress neonatal adrenal development if given later.

Tocolysis - The evidence supports the use of first-line tocolytic treatment with beta-adrenergic agonist therapy, calcium channel blockers, or NSAIDs for short-term prolongation of pregnancy (up to 48 hours) to allow for the administration of antenatal steroids.

Fetal Neuroprotection - magnesium sulfate reduces the severity and risk of cerebral palsy in surviving infants if administered when birth is anticipated before 32 weeks of gestation.

Multiple antenatal courses have been associated with fetal adrenal suppression.  

In a RCT of antenatal corticosteroids, a reduction in birth weight and and increase in SGA infants was found, especially if more than 4 courses were given.

42 weeks or greater according to Fleischman, Oinuma and Clark- Rethinking the definition of “term pregnancy”

What is the risk of stillbirth at 40 weeks?

41 weeks?

42 weeks?

43?

40: 1 in 926

41: 1 in 826

42: 1 in 769

43: 1 in 633

What is the risk of perinatal mortality (stillbirth + early neonatal death) at 40 weeks?

42 weeks?

2-3 per 1000 deliveries 

4-7 per 1000 deliveries

(at 43 weeks is increased 4-fold)

• Uteroplacental insufficiency
• Asphyxia (with and without meconium aspiration)
• Intrauterine infection
• Neonatal acidemia
• low Apgar scores
• Macrosomia and associated:
• Prolonged labor
• CPD
• Shoulder dystocia
• Oligohydramnios
• Increased risk of cord compression
• Increased short term neonatal complications (hypoglycemia, seizures, and respiratory insufficiency)
• Meconium aspiration syndrome (tachypnea, cyanosis, and reduced pulmonary compliance)
• Independent risk factor for death in the first year of life

• Significant increase in labor dystocia (9-12% vs 2-7% at term)
• Increase in perineal injury (3rd & 4th degree lacerations)
• Increase in operative vaginal delivery
• Doubling of cesarean delivery with associated risks
• Increase in maternal morbidity due to chorioamnionitis, severe perineal lacerations c-section, severe PP hemorrhage, and endomyometritis.

the midwife uses her index finger as far as possible through the internal os and rotates the distal end of her finger slowly between the lower uterine segment and the membranes (shortens gestation by an average of 2-5 days)

• use electric breast pump for 15 mins on then 15 mins off
• stimulation of breasts with gentle massage and warm moist cloth for 1 hour, 3 times a day
• or massage each breast alternately for a total of 3 hours a day
• women should be counseled to limit nipple contact so that hyperstimulation of the uterus does not occur

• oral ingestion of 60 mg mixed in apple or orange juice (best after a good nights’ sleep and 1-2 hours before the woman gets up for the day)  

often recommended to soften the cervix ( since semen contains prostaglandins) but there isn’t sufficient evidence to support it (though it’s not a problem as long as a woman’s membranes are intact)

But...
“Reported sexual intercourse at term was associated with earlier onset of labor and reduced requirement for labor induction at 41 weeks.”
Obstet Gynecol. 2006 Jul;108(1):134-40.

Evening primrose oil

Red raspberry leaf

Black cohosh 

Blue cohosh

(All need further study)

What medication for labor induction stimulates uterine contraction by activating G-protein receptors that trigger increases in intracellular Ca levels in myofibrils, increase local prostaglandin production, and stimulate contractions?

Onset

IM: 3-5 minutes

IV: ~1 minute

Duration: 

IM: 2-3 hours

IV: 1 hour

What is the half life of oxytocin?

How is it excreted?

• 1-6 minutes; decreased in late pregnancy and during lactation

  
  
  Excreted in urine.

• Metabolism: Hepatic; rapidly de-esterified to misoprostol acid (active)

• Half-life elimination: Misoprostol acid: 20-40 minutes

• Excretion: Urine (80%)

• Onset of action (uterine contractions): Vaginal suppository: Within 10 minutes

  Time to peak, plasma: Endocervical gel: 30-45 minutes

• Duration: Vaginal insert: 0.3 mg/hour over 12 hours; Vaginal suppository: Up to 2-3 hours

  
  

• Metabolism: Metabolized in the lungs; forms metabolites which are further metabolized in the liver and kidney

• Half-life elimination: 2.5-5 minutes
• Excretion: Primarily urine; feces (small amounts)

Absorption: Oral: rapid

Time to peak: Oral: 90 minutes; Range: Single dose: 1-2 hours, Multiple doses: 1-4 hours

• Metabolism: Hepatic via CYP3A4 to three metabolites (active)

• Half-life elimination: Single dose: Terminal: 18 hours following a slower phase where 50% eliminated between 12-72 hours; Multiple doses (600 mg/day): 85 hours

• Excretion: Feces (83%); urine (9%)

Dilation

Effacement

Length

Station

Consistency

Cx position

0=closed

1= 1-2 cm

2 = 3-4 cm

3 = 5+ cm

0 = 0-30

1 = 40-50

2 = 60-70

3 = 80+

0 = >4

1 = 2-4

2 = 1-2

3 = 1-2

0 = -3

1 = -2

2 =  -1 or 0

3 = +1 or +2

0 = firm

1 = medium

2= soft

3=

0= posterior

1= mid

2=anterior

3=

Diagnostic

1. Review dating criteria (LMP, HCG, initial visit, u/s, FHTs, etc)

2. Leopolds for EFW

3. Examine cervix.  Bishops >5 considered favorable.

Therapeutic

1. Consider sweeping of membranes at 38-41 weeks, discuss with client.

2. See alternate methods of induction (Castor oil, breast stimulation)

Education

1. Offer induction at 41 weeks or expectant management.  See counseling guidelines (pp169-170)

2. Post dates management (tests, induction methods, r/b/a)

3. Encourage sexual intercourse (!!!)

Follow-Up

1. Initiate biweekly antenatal testing by 41 weeks, including NST and AFI.

2. Initiate kick count at 40-41 weeks.  Client should call if <10 movements in 2-hour period.  Give client record and explain how to use it.

In one approach, the woman lies on her side and counts distinct fetal movements . Perception of 10 distinct movements in a period of up to 2 hours is considered reassuring. Once 10 movemenrs have been perceived, the count may be discontinued.

In another approach, women are instructed to count fetal movements for 1 hour three times per week (10). The count is considered reassuring if it equals or exceeds the woman’s previously established baseline count. In the absence of a reassuring count, further fetal assessment is recommended.

With the patient in the lateral recumbent position, fetal heart rate and uterine contractions are recorded with an external fetal monitor. If at least three spontaneous contractions of 40 seconds’ duration each or longer are present in 10 min, no uterine stimulation is necessary. If fewer than three contractions of at least 40 seconds’ duration occur in 10 minutes, contractions are induced with either nipple stimulation or intravenous administration of dilute oxytocin.

Nipple stimulation: woman is instructed to rub one nipple through her clothing for 2 minutes or until a contraction begins

if the use of oxytocin is preferred, an intravenous infusion of dilute oxytocin may be initiated at a rate of 0.5 mU/min and doubled every 20 minutes until an adequate contraction pattern is achieved .

• no late or significant variable decelerations

• late decelerations following 50% or more of contractions (even if the contraction frequency is fewer than three in 10 minutes)

• fetal heart rate decelerations that occur in the presence of contractions more frequent than every 2 minutes or lasting longer than 90 seconds

With the patient in lateral position, FHT are monitored with an external transducer.The tracing is observed for accelerations that peak (but do not necessarily remain) at least 15 beats per minute above the baseline and last 15 seconds from baseline to baseline. It may be necessary to continue the tracing for 40 minutes or longer to take into account the variations of the fetal sleep-wake cycle.

Ideally, the patient should not have smoked recently, because this may adversely affect test results .

NST is considered reactive (normal) if there are two or more fetal heart rate accelerations (accelerations that peak at least 15 beats per minute above the baseline and last 15 seconds from baseline to baseline) within a 20-minute period, with or without fetal movement discernible by the woman .

A nonreactive NST is one that lacks sufficient fetal heart rate accelerations over a 40- minute period.

Variable decelerations may be observed in up to 50% of NSTs. If nonrepetitive and brief (~30 seconds), they indicate neither fetal compromise nor the need for obstetric intervention.

Repetitive variable decelerations (at least 3 in 20 minutes), even if mild, have been associated with an increased risk of cesarean delivery for a nonreassuring intrapartum fetal heart rate pattern.

1. Nonstress test (which, if all four ultrasound components are normal, may be omitted without compromising the validity of the test results)
2. Fetal breathing movements (one or more episodes of rhythmic fetal breathing movements of 30 seconds or more within 30 minutes)
3. Fetal movement (three or more discrete body or limb movements within 30 minutes)
4. Fetal tone (one or more episodes of extension of a fetal extremity with return to flexion, or opening or closing of a hand)
5. Determination of the amniotic fluid volume (a single vertical pocket of amniotic fluid exceeding 2 cm is considered evidence of adequate amniotic fluid)

Each of the five components is assigned a score of either 2 (normal or present as defined previously) or 0 (abnormal, absent, or insufficient).

A composite score of 8 or 10 is normal, a score of 6 is considered equivocal, and a score of 4 or less is abnormal

What are the components for a modifed BPP?

What do they indicate about fetal well-being?

NST

+ 

AFI

NST is a short-term indicator of fetal acid-base status

AFI is an indicator of long-term placenta function

Reactive NST

+

AFI >5