INTRODUCTION
¶ 1 Utah’s criminal homicide statute provides that a person may be prosecuted for causing the death of an unborn child. This interlocutory appeal concerns (1) whether the term “unborn child” is unconstitutionally vague both on its face and as applied, and (2) whether the criminal homicide and aggravated murder statutes violate the federal and state guarantees of equal protection.
¶ 2 Defendant Roger Martin MacGuire has been charged with two counts of aggravated murder for allegedly killing his former wife and her unborn child. In a motion to dismiss Count I in part and Count II in its entirety, defendant contended he could not be prosecuted for killing the unborn child or be charged with aggravated murder based on that killing because Utah’s criminal homicide and aggravated murder statutes are unconstitutional. The district court denied defendant’s motion to dismiss and defendant peti*1173tioned for review of the interlocutory order. We affirm.
BACKGROUND
¶ 3 Defendant has been charged with the murder of his former wife, Susan C. MacGuire, and her unborn child. According to accounts presented at the preliminary hearing,1 defendant learned, several days pri- or to the murder, that Ms. MacGuire was engaged and expecting a baby. He called his former father-in-law on January 14, 2001, to confirm the information. On the morning of January 15, 2001, defendant allegedly entered the insurance office where Ms. MacGuire worked and shot her four times.
¶ 4 One of the bullets entered Ms. MacGuire at the base of her neck and traveled through the occipital bone of the skull. A second bullet entered and exited her left forearm. A third bullet entered the side of her abdomen approximately at the waistline and pierced her abdominal wall and small intestine. A fourth bullet entered her abdomen and traveled through her uterus, lodging in the right wall of her pelvis.2
¶ 5 This fourth bullet lethally injured the unborn child Ms. MacGuire was carrying. It severed the umbilical cord and traveled through the placenta and unborn child itself before lodging in the pelvic wall. The medical examiner estimated that the gestational age of the unborn child was between thirteen and fifteen weeks at the time of death. Ms. MacGuire was life-flighted to a hospital where she died later that day.
¶ 6 Defendant has been charged with two counts of aggravated murder. Count I of the information charges defendant with aggravated murder for the death of Ms. MacGuire and alleges two aggravating circumstances; namely, (1) two persons were killed during the same criminal episode, and (2) the homicide was committed to retaliate against or prevent Ms. MacGuire from testifying, providing evidence, or participating in a legal proceeding or official investigation.3 Count II of the information charges defendant with aggravated murder for the death of the unborn child during a criminal episode in which two persons were killed.
¶ 7 Defendant filed a motion to dismiss the first aggravating factor in Count I and to dismiss Count II in its entirety on the basis that an unborn child is not a person under the aggravated murder statute, and the criminal homicide and aggravated murder statutes are unconstitutionally vague and violate equal protection guarantees. The district court denied defendant’s motion, and defendant filed a petition for interlocutory appeal. We have jurisdiction pursuant to Utah Code Ann. section 78-2-2(3)(h) (2002).
ANALYSIS
I. STANDARD OF REVIEW
¶ 8 Whether the district court properly interpreted Utah’s criminal homicide and aggravated murder statutes “is a question of law that we review for correctness.” State v. Gomez, 2002 UT 120, ¶ 11, 63 P.3d 72. Likewise, “[w]hether a statute is constitutional is a question of law [that] we review for correctness, giving no deference to the trial court.” State v. Daniels, 2002 UT 2, ¶ 30, 40 P.3d 611 (citing State v. Mohi, 901 P.2d 991, 995 (Utah 1995)). Moreover, “legislative enactments are presumed to be constitutional.” Greenwood v. City of North Salt Lake, 817 P.2d 816, 819 (Utah 1991) (citations omitted). As a result, “those who challenge a statute ... as unconstitutional bear” a heavy “burden of demonstrating its unconstitutionality.” Id. (citations omitted); accord Mohi, 901 P.2d at 1009 (Russon, J., concurring and dissenting) (stating the burden of “challenging the constitutionality of a *1174statute” is “a heavy one”); United States v. Nat’l Dairy Prods. Corp., 372 U.S. 29, 32, 83 S.Ct. 594, 9 L.Ed.2d 561 (1963) (noting that a “strong presumptive validity” attaches to legislative acts).
II. VAGUENESS CHALLENGE
¶ 9 Defendant challenges the criminal homicide and aggravated murder statutes of the Utah Code as being unconstitutionally vague both facially and as applied. The criminal homicide statute provides as follows:
(a) A person commits criminal homicide if he intentionally, knowingly, recklessly, with criminal negligence, or acting with a mental state otherwise specified in the statute defining the offense, causes the death of another human being, including an unborn child.
(b) There shall be no cause of action for criminal homicide for the death of an unborn child caused by an abortion.
Utah Code Ann. § 76-5-201(1) (1999) (emphasis added).
¶ 10 The aggravated murder statute provides, in relevant part, as follows:
(1) Criminal homicide constitutes aggravated murder if the actor intentionally or knowingly causes the death of another under any of the following circumstances:
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(b) the homicide was committed incident to one act, scheme, course of conduct, or criminal episode during which two or more persons were killed ....
Id. § 76-5-202(l)(b) (emphasis added).
¶ 11 Defendant contends the term “unborn child” in the criminal homicide statute is unconstitutionally vague because the legislature failed to define the term and, absent that definition, it lacks a clear and specific meaning. Moreover, because “unborn child” is not defined, defendant contends the terms “another” and “persons” in the aggravated murder statute are also unconstitutionally vague because it is impossible to know when an unborn child achieves the status of a person. We disagree.
A. Void for Vagueness Doctrine
¶ 12 Where, as here, a statute “implicates no constitutionally protected conduct,” a court will uphold a facial vagueness challenge “only if the [statute] is impermissi-bly vague in all of its applications.” Village of Hoffman Estates v. The Flipside, Hoffman Estates, Inc., 455 U.S. 489, 494-95, 102 S.Ct. 1186, 71 L.Ed.2d 362 (1982). A statute that is clear as applied to a particular complainant cannot be considered impermissibly vague in all of its applications and thus will necessarily survive a facial vagueness challenge. See id. at 495, 102 S.Ct. 1186 (“A plaintiff who engages in some conduct that is clearly proscribed cannot complain of the vagueness of the law as applied to the conduct of others.”).
¶ 13 In order to establish that the complained-of provisions are impermissibly vague, a defendant must demonstrate either (1) that the statutes do not provide “the kind of notice that enables ordinary people to understand what conduct [is prohibited],” or (2) that the statutes “encourage arbitrary and discriminatory enforcement.” State v. Honie, 2002 UT 4, ¶ 31, 57 P.3d 977 (citing Kolender v. Lawson, 461 U.S. 352, 357, 103 S.Ct. 1855, 75 L.Ed.2d 903 (1983)). Defendant has failed to establish that the statutes violate either test.
B. Notice that Conduct Is Prohibited
¶ 14 “Vagueness questions are essentially procedural due process issues, i.e., whether the statute adequately notices the proscribed conduct.” State v. Frampton, 737 P.2d 183, 191-92 (Utah 1987) (citation omitted). If a statute “ ‘is sufficiently explicit to inform the ordinary reader what conduct is prohibited,’ ” it is not unconstitutionally vague. Id. (quoting State v. Theobald, 645 P.2d 50, 51 (Utah 1982)). Here, defendant contends that the criminal homicide and aggravated murder statutes do not provide adequate notice about what type of conduct is prohibited because an ordinary person is left to guess at the meaning of the term “unborn child.” Thus, defendant reasons, a person cannot “ ‘steer between lawful and unlawful conduct.’ ” Village of Hoffman Estates, 455 U.S. at 498, 102 S.Ct. 1186 (quoting Grayned *1175v. City of Rockford, 408 U.S. 104, 108-09, 92 S.Ct. 2294, 33 L.Ed.2d 222 (1972)). We therefore must determine whether the term “unborn child” is sufficiently definite to provide adequate notice as to what conduct is proscribed.
1. Plain Meaning of “Unborn Child”
¶ 15 “In considering the meaning of a [statutory] provision, the analysis begins with the plain language of the provision.... We need not look beyond the plain language unless we find some ambiguity in it.” Utah Sch. Bds. Ass’n v. State Bd. of Educ., 2001 UT 2, ¶ 13, 17 P.3d 1125 (citation omitted). Moreover, “[t]he plain language of a statute is to be read as a whole, and its provisions interpreted in harmony with other provisions in the same statute and with other statutes under the same and related chapters.” Lyon v. Burton, 2000 UT 19, ¶17, 5 P.3d 616 (internal quotations and citations omitted).
¶ 16 In State v. Larsen, 578 P.2d 1280, 1281-82 (Utah 1978), we held that a person could not be convicted of automobile homicide for causing the death of a twenty-six-week-old fetus because a fetus was not specifically recognized in statute as a human being. In response to our decision, the legislature amended the criminal homicide statute4 to provide that a person is guilty of criminal homicide if, acting with the requisite mental state, the person “causes the death of another human being, including an unborn child.” Utah Code Ann. § 76-5-201(l)(a) (1999). By its plain meaning the statute recognizes that an unborn child is a human being.
¶ 17 Defendant contends nevertheless that the statute is unconstitutionally vague because “it is impossible to ascertain from statute, or otherwise, when unborn childhood begins.” As a result, he argues, an ordinary person is left to guess whether his or her conduct falls within the parameters of the statute because it is unknown at what point a potential life actually becomes an unborn child.
¶ 18 Although the defendant attempts “to inject doubt as to the meaning of words where no doubt would be felt by the normal reader,” such straining “is not required by the ‘void for vagueness’ doctrine, and we will not indulge in it” here. United States v. Powell, 423 U.S. 87, 93, 96 S.Ct. 316, 46 L.Ed.2d 228 (1975). Instead, we will attribute to the legislature the commonsense meaning of the term “unborn child.” Id.
¶ 19 “Unborn child” is defined as “[t]he individual human life in existence and developing prior to birth.” Black’s Law Dictionary 1058 (abridged 6th ed.1991). See also Merriam-Webster’s Collegiate Dictionary 1285 (10th ed.1998) (defining “unborn” as “not born,” “not brought into life,” or “existing without birth”). Therefore, without modifying language to the contrary, the commonsense meaning of the term “unborn child” is a human being at any stage of development in útero because once fertilization occurs, an unborn child is an “individual human life” that is “in existence and developing prior to birth.”
2. Definition of “Unborn Child” in Other Chapters of the Utah Criminal Code and in Other Jurisdictions
¶ 20 This definition is consistent with how the term “unborn child” is used in other parts of the criminal code. For example, in a chapter of the criminal code that regulates abortions, the legislature mandates that informational materials be made available to any person contemplating an abortion. Utah Code Ann. § 76-7-305.5(1) (1999). The informational materials must include “the probable anatomical and physiological characteristics of the unborn child at two-week gestational increments from fertilization to full term, accompanied by pictures or video segments representing the development of an unborn child at those gestational increments.” Id. § 76-7-305.5(l)(b) (emphasis added).
¶ 21 Additionally, the legislature mandates that the Utah Department of Health produce a videotape “show[ing] an ultrasound of the *1176heart beat of an unborn child at three weeks gestational age, at six to eight weeks gestational age, and each month thereafter, until lip weeks gestational age.” Id. § 76-7-305.5(4) (emphasis added). Thus, when the plain language of the criminal homicide statute is read in harmony with other chapters of the criminal code, it is clear that the legislature intended the term “unborn child” to encompass the period from fertilization to birth.
¶ 22 Finally, ease law from other jurisdictions recognizes that “[tjhere is no unconstitutional vagueness in the description of the unborn as the ‘unborn child.’ ” Brinkley v. Georgia, 253 Ga. 541, 322 S.E.2d 49, 53 (1984) (affirming convictions of co-defendants for violation of Georgia’s feticide statute). Specifically, the Georgia Supreme Court noted that the term “unborn child” in Georgia’s feticide statute would have “clearly coverfed] the entire period of pregnancy” if the legislature had not limited it to the period where an unborn child is “so far developed as to be ordinarily called ‘quick.’ ” Id. at 51, 53 (quoting Ga.Code Ann. § 16-5-80 (1982)). The court’s conclusion that the state’s feticide statute was not unconstitutionally vague was later followed by the Eleventh Circuit Court of Appeals. Smith v. Newsome, 815 F.2d 1386,1387-88 (11th Cir.1987).
3. The Recent Amendment to the Criminal Homicide Statute Does Not Demonstrate that the Term “Unborn Child” Is Unconstitutionally Vague
¶ 23 Defendant also contends that the legislature’s recent amendment to the statute demonstrates “in and of itself’ that the term “unborn child” is unconstitutionally vague. Effective May 6, 2002, the legislature inserted “at any stage of its development” after the term “unborn child.” Utah Code Ann. § 76-5-201(l)(a) (Supp.2003). Hence, the statute now reads that “[a] person commits criminal homicide if he ... causes the death of another human being, including an unborn child at any stage of its development.” Id. (emphasis added).
¶24 Although we acknowledge that the statute is now more precise, this does not mean that the statute prior to amendment was unconstitutionally vague. Indeed, the United States Supreme Court has stated that “[t]he fact that Congress might, without difficulty, have chosen ‘[cjlearer and more precise language’ equally capable of achieving the end which it sought does not mean that the statute which it in fact drafted is unconstitutionally vague.” United States v. Powell, 423 U.S. 87, 94, 96 S.Ct. 316, 46 L.Ed.2d 228 (1975) (quoting United States v. Petrillo, 332 U.S. 1, 7, 67 S.Ct. 1538, 91 L.Ed. 1877 (1947)). Here, the legislature drafted a statute that achieved the end that it sought, namely, to include an unborn child within the definition of a human being for purposes of the criminal homicide statute. While adding the phrase “at any stage of its development” made the statute more precise, it did not alter the commonsense meaning of “unborn child.” We therefore conclude that the term “unborn child” provides the kind of notice that enables ordinary people to understand what conduct is statutorily prohibited.
4. The Term “Unborn Child” Does Not Render the Aggravated Murder Statute Unconstitutionally Vague
¶ 25 Finally, defendant contends that because the term “unborn child” fails to provide adequate notice concerning what conduct is proscribed, it renders the aggravated murder statute unconstitutionally vague. We disagree.
¶ 26 The criminal homicide statute expressly includes an unborn child within its definition of a human being. Utah Code Ann. § 76-5-201(l)(a) (1999). This definition of a human being is imported into the aggravated murder statute because of the statutory link between the criminal homicide statute and the aggravated murder statute.
¶27 Specifically, the aggravated murder statute provides that “[cjriminal homicide constitutes aggravated murder if the actor intentionally or knowingly causes the death of another ” under any one of seventeen circumstances, including killing two or more persons during the same criminal episode. Utah Code Ann. § 76-5-202(l)(b) (1999) (emphasis added).
*1177¶28 Defendant argues that because the terra “unborn child” is not defined in the criminal homicide statute, it also renders the terms “another” and “persons” in the aggravated murder statute unconstitutionally vague because it is impossible to know when an unborn child achieves the status of a human being. Because we have already concluded, however, that the term “unborn child” provides the kind of notice that enables ordinary people to understand what conduct is statutorily prohibited, the term cannot render the words “another” and “persons” unconstitutionally vague. We now turn to a discussion of defendant’s second argument; namely, that the criminal homicide statute encourages arbitrary and discriminatory enforcement.
C. Defining Conduct Sufficiently to Preclude Arbitrary and Discriminatory Enforcement
¶29 In addition to providing adequate notice about what conduct is proscribed, the “void for vagueness” doctrine requires the legislature to “define the criminal offense ... in a manner that does not encourage arbitrary and discriminatory enforcement.” Kolender v. Lawson, 461 U.S. 352, 357, 103 S.Ct. 1855, 75 L.Ed.2d 903 (1983) (citations omitted). In other words, the legislature must “ ‘establish minimal guidelines to govern law enforcement.’ ” Id. at 358, 103 S.Ct. 1855 (quoting Smith v. Goguen, 415 U.S. 566, 574, 94 S.Ct. 1242, 39 L.Ed.2d 605 (1974)).
¶ 30 Here, defendant contends that “[t]he Legislature’s failure to clearly and specifically define the term ‘unborn child’ not only encourages but facilitates arbitrary and discriminatory enforcement” because “the prosecutor is left to speculate at what point an unborn child becomes a person for enforcement purposes.” Additionally, defendant contends that enforcement decisions will be made “at least in part, by the prosecutor’s own thoughts or beliefs concerning fetal rights,” because the statute fails to provide adequate guidance.
¶ 31 This argument fails for the same reason that defendant’s argument concerning adequacy of notice fails. Defendant’s argument is premised on the notion that the legislature had to define the term “unborn child” in order for the term to have a definite meaning. The “void for. vagueness” doctrine does -ndt, howdver, require a legislature to define terms that are readily ascertainable. Because the term “unborn child” has a straightforward definition, as we have discussed above, a prosecutor is not left to speculate, as to the statute’s meaning. Thus, the legislature adequately established minimal guidelines for the enforcement of the statute. We therefore conclude that the statute is not unconstitutionally vague either facially or as applied because it does not encourage or facilitate arbitrary and discriminatory enforcement.
¶ 32 In sum, we conclude that the term “unborn child” is not unconstitutionally vague because, absent modifying language to the contrary, it clearly encompasses a human being at any stage of development in útero. The statute thus provides adequate notice to an ordinary person about what conduct is proscribed. Moreover, because the meaning of the term is readily ascertainable, its inclusion does not encourage or facilitate arbitrary and discriminatory enforcement. Hence, the criminal homicide and aggravated murder statutes-are sufficiently clear as applied to the defendant and cannot be 'considered “impermissibly vague in all [their] applications.” Indeed, given our plain, commonsense reading of the term “unborn child,” it is difficult to imagine any circumstance in which the meaning would be unclear. Thus, defendant’s vagueness challenges fail, both facially and'as applied, and we affirm the decision of the district 'court on this issue.
III. EQUAL PROTECTION
33 In addition to challenging the criminal homicide and aggravated murder statutes for vagueness, • defendant contends the statutes violate equal- protection guarantees under the Fourteenth' .Amendment to the United States Constitution'and article 1, section 24 of the Utah Constitution.. Specifically, defendant contends that because physicians are not prosecuted for aborting fetuses and microbiologists, are not prosecuted for *1178destroying fertilized embryos for stem cell research, the statute “does not apply equally to all persons within the class,” namely, those who cause the death of an unborn child. Hence, according to defendant, the statute is unconstitutional.
¶ 34 The State argues that we should not address defendant’s argument because he did not raise it before the district court. Although we note that defendant did make reference to equal protection guarantees in his motion to dismiss, we need not address whether such references were sufficient to preserve this issue for appeal because defendant failed to petition for interlocutory review of the issue.
¶ 35 Rule 5 of the Utah Rules of Appellate Procedure specifies that “[a]n appeal from an interlocutory order may be sought ... by filing a petition for 'permission to appeal from the interlocutory order.” Utah R.App. P. 5(a) (emphasis added). The petition must contain “[t]he issue presented” and a “concise analysis of the statutes, rules[,] or cases believed to be determinative of the issue stated.” Id. at 5(c)(l)(B)-(C).
¶ 36 Here, defendant’s petition for interlocutory appeal did not address the equal protection issue. We therefore did not grant permission for defendant to appeal this issue. Moreover, because the petition made no reference to the equal protection argument, and did not provide a concise analysis of the legal authority, the State was denied the opportunity to respond to this issue in its Opposition to Petition for Permission to Appeal from Interlocutory Order. We therefore decline to address defendant’s equal protection argument.
CONCLUSION
¶ 37 In summary, the term “unborn child” does not render Utah’s criminal homicide and aggravated murder statutes unconstitutionally vague. The criminal homicide statute provides that a person may be prosecuted for causing the death of a human being, including an unborn child. Because the commonsense meaning of the term “unborn child” is a human being at any stage of development in útero, the term provides sufficient notice to an ordinary person about what conduct is proscribed. Moreover, the term does not encourage arbitrary and discriminatory enforcement because its meaning is readily ascertainable. Consequently, we conclude that the term “unborn child” does not render the criminal homicide statute unconstitutionally vague. We also conclude that the terms “another” and “persons” are not rendered unconstitutionally vague in the aggravated murder statute by the fact that they encompass the term “unborn child.” We therefore affirm the district court on this issue.
¶38 We decline to address defendant’s equal protection argument. Although there is some question concerning whether defendant adequately raised this issue below, we need not determine whether the issue was adequately preserved because defendant did not petition for interlocutory review of his equal protection argument. As a result, we did not grant permission to defendant to appeal this issue and we decline to address it.
¶ 39 The district court’s decision to deny defendant’s motion to dismiss is affirmed.
¶ 40 Justice WILKINS, Justice PARRISH, and Judge NEHRING concur in Associate Chief Judge DURRANT’S opinion.. The facts included in this section have not been established at trial but remain mere allegations.
. Although the medical examiner did not specify the exact order of the gunshot wounds, she did testify that the gunshot wounds to the abdomen likely occurred prior to the gunshot wound to the head. She had no opinion as to when the.gunshot wound to the arm occurred.
.The second aggravating factor is based upon the allegation that when defendant arrived at Ms. MacGuire's workplace just prior to the murder, Ms.-MacGuire threatened to call the police and report defendant for violating a protective order that was in place at the time.
. The criminal homicide statute is statutorily linked to the automobile homicide statute, which sets forth the conditions under which criminal homicide constitutes the specific crime of automobile homicide. Utah Code Ann. § 76-5-207(l)(a), (2)(a) (1999).