Preterm Birth Flashcards
Define low birthweight vs preterm birth
Low birthweight is for babies who were born too small
Preterm birth is for babies who were born TOO EARLY
Define the different ranges of low birthweight babies (3)
Normal = 3000
Low birthweight = 1500g - 2500g
Very low birthweight = 500 - 1500
Extremely low birthweight = 500 - 1000
Define the different ranges of preterm and term births
Early preterm - before the 34th week
Late preterm - 34-36 weeks
Early term - 37-39 weeks
Late term - 40 - 42 weeks
additional note:
preterm = before 37 weeks
term = 37-42
post-term = >42 weeks
What are the three main causes of preterm birth?
How do you differentiate two of the answers?
- Spontaneous preterm labor
- Preterm premature rupture of membranes
- Multifetal pregnancy
Spontaneous labor with intact membranes must be differentiated from preterm premature rupture of membranes AS THE CAUSE of preterm birth
What are the FOUR MAJOR CAUSES of spontaneous preterm labor?
- Uterine distention (multifetal pregnancies, polyhydramnios, )
- Maternal-fetal stress
- Premature cervical changes
- Infection
For Uterine Distention, what are two well-recognized risks?
Multiple pregnancies (kaya nga overdistended)
Hydramnios
How does uterine distention lead to preterm labor?
hint: it leads to a loss of ______ due to the release of (3)
Leads to a loss of quiescence
Due to the release of:
- contraction associated protein
- gastrin releasing peptides
- stretch induced potassium channel - TREK-1
Maternal fetal stress leading to spontaneous labor is caused by the elevation of what hormone due to stress?
cortisol
Stress leads to increase in CRH -> works with ACTH to induce maternal and fetal steroid production -> increase in fetal DHEAS -> which leads to an increase in estriol.
cortisol and estriol both lower uterine quiescence
How does infection cause preterm labor?
Expound on how these three come from infection and lead to preterm labor:
- Inflammation
- Prostaglandins
- Premature activation of the fetal HPA
When the mother gets infected during pregnancy, the bacteria releases endotoxins
The endotoxins reach the leukocytes which produce cytokines and chemokines
Cytokines and chemokines will then promote cascades leading to:
- inflammation -> PROTEASE synthesis -> cervical ripening + Preterm prematuer rupture of membranes -> preterm labor
- Prostaglandins -> cervical ripening + myometrial activation -> preterm labor
- activation of fetal HPA -> release of CRH -> ACTH -> fetal DHEAs -> estriol -> myometrial activation -> preterm labor
alternatively -> CRH -> ACTH -> cortisol -> prostaglandins -> myometrial activation + cervical ripening
Give the THREE sources of intrauterine infection
what is the most common route?
- transplacental
- retrograde flow
- Ascending infection of bacteria -> MOST COMMON ROUTE
Give the FOUR microbes associated with preterm birth
- Gardnerella vaginalis
- Fusobacterium species
- Mycoplasma hominis
- Ureaplasma urealyticum
Give the FOUR categories of bacterial infection in pregnant women
- Category I - Bacterial vaginosis
- Category II - Decidual infection
- Category III - Amniotic infection
- Category IV - Fetal systemic infection
Give the definition of preterm premature rupture of membranes
Rupture of the membranes BEFORE 37 weeks are completed AND before the onset of labor
(difference from simple PROM is that here it is below 37 weeks, not just before the onset of labor)
What are major predisposing events to PPROM
- Intrauterine infections
- Oxidative stress
- Early cell senescence
Give 10 lifestyle factors that contribute to preterm labor (9)
- Cigarette smokinh
- Inadequate maternal weight gain
- Illicit drug use
- Extremes of weight
- Extremes of age
- poverty
- Short stature
- VITAMIN C DEFICIENCY
- Psychological factors such as anxiety, depression, stress